Sequence diverging to infiinity definition question












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Let $a_n$ be a real sequence



I know a definition for a sequence to diverge to infinity, that being: if for all m ∈ real numbers, exists N ∈ natural numbers :



$a_n > m , n≥N$



Is the following definition a proper definition for a real sequence to diverge to infinity as well?



For all m ∈ real numbers, exists $a_n$ ∈ real numbers :
$a_n > m $



Otherwise, I would like some clarification, please.










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    No. Consider $a_n$ such that $a_{2n}=0$ and $a_{2n+1}=n$ for $n in mathbb{N}$. Then $a_n$ does not converge to $infty$, but satisfies your "definition".
    $endgroup$
    – greelious
    Jan 7 at 22:54


















0












$begingroup$


Let $a_n$ be a real sequence



I know a definition for a sequence to diverge to infinity, that being: if for all m ∈ real numbers, exists N ∈ natural numbers :



$a_n > m , n≥N$



Is the following definition a proper definition for a real sequence to diverge to infinity as well?



For all m ∈ real numbers, exists $a_n$ ∈ real numbers :
$a_n > m $



Otherwise, I would like some clarification, please.










share|cite|improve this question









$endgroup$








  • 1




    $begingroup$
    No. Consider $a_n$ such that $a_{2n}=0$ and $a_{2n+1}=n$ for $n in mathbb{N}$. Then $a_n$ does not converge to $infty$, but satisfies your "definition".
    $endgroup$
    – greelious
    Jan 7 at 22:54
















0












0








0





$begingroup$


Let $a_n$ be a real sequence



I know a definition for a sequence to diverge to infinity, that being: if for all m ∈ real numbers, exists N ∈ natural numbers :



$a_n > m , n≥N$



Is the following definition a proper definition for a real sequence to diverge to infinity as well?



For all m ∈ real numbers, exists $a_n$ ∈ real numbers :
$a_n > m $



Otherwise, I would like some clarification, please.










share|cite|improve this question









$endgroup$




Let $a_n$ be a real sequence



I know a definition for a sequence to diverge to infinity, that being: if for all m ∈ real numbers, exists N ∈ natural numbers :



$a_n > m , n≥N$



Is the following definition a proper definition for a real sequence to diverge to infinity as well?



For all m ∈ real numbers, exists $a_n$ ∈ real numbers :
$a_n > m $



Otherwise, I would like some clarification, please.







sequences-and-series






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asked Jan 7 at 22:47









ValVal

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557








  • 1




    $begingroup$
    No. Consider $a_n$ such that $a_{2n}=0$ and $a_{2n+1}=n$ for $n in mathbb{N}$. Then $a_n$ does not converge to $infty$, but satisfies your "definition".
    $endgroup$
    – greelious
    Jan 7 at 22:54
















  • 1




    $begingroup$
    No. Consider $a_n$ such that $a_{2n}=0$ and $a_{2n+1}=n$ for $n in mathbb{N}$. Then $a_n$ does not converge to $infty$, but satisfies your "definition".
    $endgroup$
    – greelious
    Jan 7 at 22:54










1




1




$begingroup$
No. Consider $a_n$ such that $a_{2n}=0$ and $a_{2n+1}=n$ for $n in mathbb{N}$. Then $a_n$ does not converge to $infty$, but satisfies your "definition".
$endgroup$
– greelious
Jan 7 at 22:54






$begingroup$
No. Consider $a_n$ such that $a_{2n}=0$ and $a_{2n+1}=n$ for $n in mathbb{N}$. Then $a_n$ does not converge to $infty$, but satisfies your "definition".
$endgroup$
– greelious
Jan 7 at 22:54












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No take the sequence
$$
a_n=(-1)^nn.
$$

Under your proposed definition this sequence diverges to infinity (but it clearly does not).






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    1 Answer
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    1












    $begingroup$

    No take the sequence
    $$
    a_n=(-1)^nn.
    $$

    Under your proposed definition this sequence diverges to infinity (but it clearly does not).






    share|cite|improve this answer









    $endgroup$


















      1












      $begingroup$

      No take the sequence
      $$
      a_n=(-1)^nn.
      $$

      Under your proposed definition this sequence diverges to infinity (but it clearly does not).






      share|cite|improve this answer









      $endgroup$
















        1












        1








        1





        $begingroup$

        No take the sequence
        $$
        a_n=(-1)^nn.
        $$

        Under your proposed definition this sequence diverges to infinity (but it clearly does not).






        share|cite|improve this answer









        $endgroup$



        No take the sequence
        $$
        a_n=(-1)^nn.
        $$

        Under your proposed definition this sequence diverges to infinity (but it clearly does not).







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 7 at 22:54









        Foobaz JohnFoobaz John

        22.9k41552




        22.9k41552






























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