Pisano period upper-bound for Tribonacci (3 step Fibonacci)












0












$begingroup$


For the Pisano Period of a 2-step Fibonacci at modulo $n$ a common and simple upper bound, according to this list of open problems, is $n^2-1$. Is there a similar upper bound for the Pisano Period of the Tribonacci (3-step Fibonacci) at modulo $n$?










share|cite|improve this question









$endgroup$

















    0












    $begingroup$


    For the Pisano Period of a 2-step Fibonacci at modulo $n$ a common and simple upper bound, according to this list of open problems, is $n^2-1$. Is there a similar upper bound for the Pisano Period of the Tribonacci (3-step Fibonacci) at modulo $n$?










    share|cite|improve this question









    $endgroup$















      0












      0








      0





      $begingroup$


      For the Pisano Period of a 2-step Fibonacci at modulo $n$ a common and simple upper bound, according to this list of open problems, is $n^2-1$. Is there a similar upper bound for the Pisano Period of the Tribonacci (3-step Fibonacci) at modulo $n$?










      share|cite|improve this question









      $endgroup$




      For the Pisano Period of a 2-step Fibonacci at modulo $n$ a common and simple upper bound, according to this list of open problems, is $n^2-1$. Is there a similar upper bound for the Pisano Period of the Tribonacci (3-step Fibonacci) at modulo $n$?







      number-theory fibonacci-numbers






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Dec 4 '18 at 15:23









      AstheroxAstherox

      31




      31






















          1 Answer
          1






          active

          oldest

          votes


















          3












          $begingroup$

          Yes, $n^3-1$.



          Consider any constant-coefficient linear recursion of order $m$. The values mod $n$ are determined by any $m$-tuple of consecutive values mod $n$. There are $n^m$ possible $m$-tuples mod $n$, but if $(0,ldots, 0)$ occurs the other terms would have to be all $0$. Thus if the sequence is nontrivial there are at most $n^m-1$ distinct possible $m$-tuples, and so the period will have to be at most $n^m-1$.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Do you know if this bound is sharp in general? I know it's sharp if $n = p$ is prime; then you can consider a recurrence with characteristic polynomial the minimal polynomial of a generator of the multiplicative group of $mathbb{F}_{p^m}$.
            $endgroup$
            – Qiaochu Yuan
            Dec 4 '18 at 20:25






          • 1




            $begingroup$
            No, it won't be sharp. Suppose $n = p q$ where $p$ and $q$ are coprime. Then the sequence mod $p$ has period at most $p^m-1$ and the sequence mod $q$ has period at most $q^m-1$, so the sequence mod $pq$ has period at most $(p^m-1)(q^m-1) < (pq)^m - 1$.
            $endgroup$
            – Robert Israel
            Dec 4 '18 at 20:28













          Your Answer





          StackExchange.ifUsing("editor", function () {
          return StackExchange.using("mathjaxEditing", function () {
          StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
          StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
          });
          });
          }, "mathjax-editing");

          StackExchange.ready(function() {
          var channelOptions = {
          tags: "".split(" "),
          id: "69"
          };
          initTagRenderer("".split(" "), "".split(" "), channelOptions);

          StackExchange.using("externalEditor", function() {
          // Have to fire editor after snippets, if snippets enabled
          if (StackExchange.settings.snippets.snippetsEnabled) {
          StackExchange.using("snippets", function() {
          createEditor();
          });
          }
          else {
          createEditor();
          }
          });

          function createEditor() {
          StackExchange.prepareEditor({
          heartbeatType: 'answer',
          autoActivateHeartbeat: false,
          convertImagesToLinks: true,
          noModals: true,
          showLowRepImageUploadWarning: true,
          reputationToPostImages: 10,
          bindNavPrevention: true,
          postfix: "",
          imageUploader: {
          brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
          contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
          allowUrls: true
          },
          noCode: true, onDemand: true,
          discardSelector: ".discard-answer"
          ,immediatelyShowMarkdownHelp:true
          });


          }
          });














          draft saved

          draft discarded


















          StackExchange.ready(
          function () {
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3025702%2fpisano-period-upper-bound-for-tribonacci-3-step-fibonacci%23new-answer', 'question_page');
          }
          );

          Post as a guest















          Required, but never shown

























          1 Answer
          1






          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          3












          $begingroup$

          Yes, $n^3-1$.



          Consider any constant-coefficient linear recursion of order $m$. The values mod $n$ are determined by any $m$-tuple of consecutive values mod $n$. There are $n^m$ possible $m$-tuples mod $n$, but if $(0,ldots, 0)$ occurs the other terms would have to be all $0$. Thus if the sequence is nontrivial there are at most $n^m-1$ distinct possible $m$-tuples, and so the period will have to be at most $n^m-1$.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Do you know if this bound is sharp in general? I know it's sharp if $n = p$ is prime; then you can consider a recurrence with characteristic polynomial the minimal polynomial of a generator of the multiplicative group of $mathbb{F}_{p^m}$.
            $endgroup$
            – Qiaochu Yuan
            Dec 4 '18 at 20:25






          • 1




            $begingroup$
            No, it won't be sharp. Suppose $n = p q$ where $p$ and $q$ are coprime. Then the sequence mod $p$ has period at most $p^m-1$ and the sequence mod $q$ has period at most $q^m-1$, so the sequence mod $pq$ has period at most $(p^m-1)(q^m-1) < (pq)^m - 1$.
            $endgroup$
            – Robert Israel
            Dec 4 '18 at 20:28


















          3












          $begingroup$

          Yes, $n^3-1$.



          Consider any constant-coefficient linear recursion of order $m$. The values mod $n$ are determined by any $m$-tuple of consecutive values mod $n$. There are $n^m$ possible $m$-tuples mod $n$, but if $(0,ldots, 0)$ occurs the other terms would have to be all $0$. Thus if the sequence is nontrivial there are at most $n^m-1$ distinct possible $m$-tuples, and so the period will have to be at most $n^m-1$.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Do you know if this bound is sharp in general? I know it's sharp if $n = p$ is prime; then you can consider a recurrence with characteristic polynomial the minimal polynomial of a generator of the multiplicative group of $mathbb{F}_{p^m}$.
            $endgroup$
            – Qiaochu Yuan
            Dec 4 '18 at 20:25






          • 1




            $begingroup$
            No, it won't be sharp. Suppose $n = p q$ where $p$ and $q$ are coprime. Then the sequence mod $p$ has period at most $p^m-1$ and the sequence mod $q$ has period at most $q^m-1$, so the sequence mod $pq$ has period at most $(p^m-1)(q^m-1) < (pq)^m - 1$.
            $endgroup$
            – Robert Israel
            Dec 4 '18 at 20:28
















          3












          3








          3





          $begingroup$

          Yes, $n^3-1$.



          Consider any constant-coefficient linear recursion of order $m$. The values mod $n$ are determined by any $m$-tuple of consecutive values mod $n$. There are $n^m$ possible $m$-tuples mod $n$, but if $(0,ldots, 0)$ occurs the other terms would have to be all $0$. Thus if the sequence is nontrivial there are at most $n^m-1$ distinct possible $m$-tuples, and so the period will have to be at most $n^m-1$.






          share|cite|improve this answer









          $endgroup$



          Yes, $n^3-1$.



          Consider any constant-coefficient linear recursion of order $m$. The values mod $n$ are determined by any $m$-tuple of consecutive values mod $n$. There are $n^m$ possible $m$-tuples mod $n$, but if $(0,ldots, 0)$ occurs the other terms would have to be all $0$. Thus if the sequence is nontrivial there are at most $n^m-1$ distinct possible $m$-tuples, and so the period will have to be at most $n^m-1$.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Dec 4 '18 at 15:33









          Robert IsraelRobert Israel

          320k23210462




          320k23210462












          • $begingroup$
            Do you know if this bound is sharp in general? I know it's sharp if $n = p$ is prime; then you can consider a recurrence with characteristic polynomial the minimal polynomial of a generator of the multiplicative group of $mathbb{F}_{p^m}$.
            $endgroup$
            – Qiaochu Yuan
            Dec 4 '18 at 20:25






          • 1




            $begingroup$
            No, it won't be sharp. Suppose $n = p q$ where $p$ and $q$ are coprime. Then the sequence mod $p$ has period at most $p^m-1$ and the sequence mod $q$ has period at most $q^m-1$, so the sequence mod $pq$ has period at most $(p^m-1)(q^m-1) < (pq)^m - 1$.
            $endgroup$
            – Robert Israel
            Dec 4 '18 at 20:28




















          • $begingroup$
            Do you know if this bound is sharp in general? I know it's sharp if $n = p$ is prime; then you can consider a recurrence with characteristic polynomial the minimal polynomial of a generator of the multiplicative group of $mathbb{F}_{p^m}$.
            $endgroup$
            – Qiaochu Yuan
            Dec 4 '18 at 20:25






          • 1




            $begingroup$
            No, it won't be sharp. Suppose $n = p q$ where $p$ and $q$ are coprime. Then the sequence mod $p$ has period at most $p^m-1$ and the sequence mod $q$ has period at most $q^m-1$, so the sequence mod $pq$ has period at most $(p^m-1)(q^m-1) < (pq)^m - 1$.
            $endgroup$
            – Robert Israel
            Dec 4 '18 at 20:28


















          $begingroup$
          Do you know if this bound is sharp in general? I know it's sharp if $n = p$ is prime; then you can consider a recurrence with characteristic polynomial the minimal polynomial of a generator of the multiplicative group of $mathbb{F}_{p^m}$.
          $endgroup$
          – Qiaochu Yuan
          Dec 4 '18 at 20:25




          $begingroup$
          Do you know if this bound is sharp in general? I know it's sharp if $n = p$ is prime; then you can consider a recurrence with characteristic polynomial the minimal polynomial of a generator of the multiplicative group of $mathbb{F}_{p^m}$.
          $endgroup$
          – Qiaochu Yuan
          Dec 4 '18 at 20:25




          1




          1




          $begingroup$
          No, it won't be sharp. Suppose $n = p q$ where $p$ and $q$ are coprime. Then the sequence mod $p$ has period at most $p^m-1$ and the sequence mod $q$ has period at most $q^m-1$, so the sequence mod $pq$ has period at most $(p^m-1)(q^m-1) < (pq)^m - 1$.
          $endgroup$
          – Robert Israel
          Dec 4 '18 at 20:28






          $begingroup$
          No, it won't be sharp. Suppose $n = p q$ where $p$ and $q$ are coprime. Then the sequence mod $p$ has period at most $p^m-1$ and the sequence mod $q$ has period at most $q^m-1$, so the sequence mod $pq$ has period at most $(p^m-1)(q^m-1) < (pq)^m - 1$.
          $endgroup$
          – Robert Israel
          Dec 4 '18 at 20:28




















          draft saved

          draft discarded




















































          Thanks for contributing an answer to Mathematics Stack Exchange!


          • Please be sure to answer the question. Provide details and share your research!

          But avoid



          • Asking for help, clarification, or responding to other answers.

          • Making statements based on opinion; back them up with references or personal experience.


          Use MathJax to format equations. MathJax reference.


          To learn more, see our tips on writing great answers.




          draft saved


          draft discarded














          StackExchange.ready(
          function () {
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3025702%2fpisano-period-upper-bound-for-tribonacci-3-step-fibonacci%23new-answer', 'question_page');
          }
          );

          Post as a guest















          Required, but never shown





















































          Required, but never shown














          Required, but never shown












          Required, but never shown







          Required, but never shown

































          Required, but never shown














          Required, but never shown












          Required, but never shown







          Required, but never shown







          Popular posts from this blog

          Probability when a professor distributes a quiz and homework assignment to a class of n students.

          Aardman Animations

          Are they similar matrix