Solve for the generating function with $x^1, x^5, x^{10}, x^{20}, x^{50}, x^{100}, x^{500}$
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How would you find the coefficient of $x^{2000}$ in
$ = (x^0 + x + x^2 +...)(x^0 + x^5 + x^{10} +...)(x^0 + x^{10} + x^{20}+...)(x^0 + x^{20} + x^{40} + ...)(x^0 + \
x^{50} + x^{100} +...)(x^0 + x^{100} + x^{200} +...)(x^0 + x^{500} + x^{1000} +...)$
I've been trying to use Mathematica, but it's not giving me a solution (very new at using it).
combinatorics generating-functions
asked Dec 18 '18 at 21:30
Math NewbieMath Newbie
428
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add a comment |
$begingroup$
How would you find the coefficient of $x^{2000}$ in
$ = (x^0 + x + x^2 +...)(x^0 + x^5 + x^{10} +...)(x^0 + x^{10} + x^{20}+...)(x^0 + x^{20} + x^{40} + ...)(x^0 + \
x^{50} + x^{100} +...)(x^0 + x^{100} + x^{200} +...)(x^0 + x^{500} + x^{1000} +...)$
I've been trying to use Mathematica, but it's not giving me a solution (very new at using it).
combinatorics generating-functions
asked Dec 18 '18 at 21:30
Math NewbieMath Newbie
428
$endgroup$
4
$begingroup$
You need to find non-negative integer solutions to $$a+5b+10c+20d+50e+100f+500g = 2000$$
$endgroup$
– Fly by Night
Dec 18 '18 at 21:35
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@FlybyNight could you explain how to do that?
$endgroup$
– Math Newbie
Dec 18 '18 at 21:39
$begingroup$
You can ask WA to compute the number using commandSeriesCoefficient[ 1/((1-x)*(1-x^5)*(1-x^10)*(1-x^20)*(1-x^50)*(1-x^100)*(1-x^500)),{x,0,2000}](same command should work on Mathematica), the number you want is86950230.
$endgroup$
– achille hui
Dec 18 '18 at 23:52
$begingroup$
@MathNewbie No, sorry. This is related to "partitions" and that is a very difficult combinatorial problem. en.wikipedia.org/wiki/Partition_(number_theory)
$endgroup$
– Fly by Night
Dec 19 '18 at 0:46
add a comment |
$begingroup$
How would you find the coefficient of $x^{2000}$ in
$ = (x^0 + x + x^2 +...)(x^0 + x^5 + x^{10} +...)(x^0 + x^{10} + x^{20}+...)(x^0 + x^{20} + x^{40} + ...)(x^0 + \
x^{50} + x^{100} +...)(x^0 + x^{100} + x^{200} +...)(x^0 + x^{500} + x^{1000} +...)$
I've been trying to use Mathematica, but it's not giving me a solution (very new at using it).
combinatorics generating-functions
asked Dec 18 '18 at 21:30
Math NewbieMath Newbie
428
$endgroup$
How would you find the coefficient of $x^{2000}$ in
$ = (x^0 + x + x^2 +...)(x^0 + x^5 + x^{10} +...)(x^0 + x^{10} + x^{20}+...)(x^0 + x^{20} + x^{40} + ...)(x^0 + \
x^{50} + x^{100} +...)(x^0 + x^{100} + x^{200} +...)(x^0 + x^{500} + x^{1000} +...)$
I've been trying to use Mathematica, but it's not giving me a solution (very new at using it).
combinatorics generating-functions
combinatorics generating-functions
asked Dec 18 '18 at 21:30
Math NewbieMath Newbie
428
asked Dec 18 '18 at 21:30
Math NewbieMath Newbie
428
asked Dec 18 '18 at 21:30
Math NewbieMath Newbie
428
asked Dec 18 '18 at 21:30
Math NewbieMath Newbie
428
asked Dec 18 '18 at 21:30
Math NewbieMath Newbie
428
428
4
$begingroup$
You need to find non-negative integer solutions to $$a+5b+10c+20d+50e+100f+500g = 2000$$
$endgroup$
– Fly by Night
Dec 18 '18 at 21:35
$begingroup$
@FlybyNight could you explain how to do that?
$endgroup$
– Math Newbie
Dec 18 '18 at 21:39
$begingroup$
You can ask WA to compute the number using commandSeriesCoefficient[ 1/((1-x)*(1-x^5)*(1-x^10)*(1-x^20)*(1-x^50)*(1-x^100)*(1-x^500)),{x,0,2000}](same command should work on Mathematica), the number you want is86950230.
$endgroup$
– achille hui
Dec 18 '18 at 23:52
$begingroup$
@MathNewbie No, sorry. This is related to "partitions" and that is a very difficult combinatorial problem. en.wikipedia.org/wiki/Partition_(number_theory)
$endgroup$
– Fly by Night
Dec 19 '18 at 0:46
add a comment |
4
$begingroup$
You need to find non-negative integer solutions to $$a+5b+10c+20d+50e+100f+500g = 2000$$
$endgroup$
– Fly by Night
Dec 18 '18 at 21:35
$begingroup$
@FlybyNight could you explain how to do that?
$endgroup$
– Math Newbie
Dec 18 '18 at 21:39
$begingroup$
You can ask WA to compute the number using commandSeriesCoefficient[ 1/((1-x)*(1-x^5)*(1-x^10)*(1-x^20)*(1-x^50)*(1-x^100)*(1-x^500)),{x,0,2000}](same command should work on Mathematica), the number you want is86950230.
$endgroup$
– achille hui
Dec 18 '18 at 23:52
$begingroup$
@MathNewbie No, sorry. This is related to "partitions" and that is a very difficult combinatorial problem. en.wikipedia.org/wiki/Partition_(number_theory)
$endgroup$
– Fly by Night
Dec 19 '18 at 0:46
4
4
$begingroup$
You need to find non-negative integer solutions to $$a+5b+10c+20d+50e+100f+500g = 2000$$
$endgroup$
– Fly by Night
Dec 18 '18 at 21:35
$begingroup$
You need to find non-negative integer solutions to $$a+5b+10c+20d+50e+100f+500g = 2000$$
$endgroup$
– Fly by Night
Dec 18 '18 at 21:35
$begingroup$
@FlybyNight could you explain how to do that?
$endgroup$
– Math Newbie
Dec 18 '18 at 21:39
$begingroup$
@FlybyNight could you explain how to do that?
$endgroup$
– Math Newbie
Dec 18 '18 at 21:39
$begingroup$
You can ask WA to compute the number using command
SeriesCoefficient[ 1/((1-x)*(1-x^5)*(1-x^10)*(1-x^20)*(1-x^50)*(1-x^100)*(1-x^500)),{x,0,2000}] (same command should work on Mathematica), the number you want is 86950230.$endgroup$
– achille hui
Dec 18 '18 at 23:52
$begingroup$
You can ask WA to compute the number using command
SeriesCoefficient[ 1/((1-x)*(1-x^5)*(1-x^10)*(1-x^20)*(1-x^50)*(1-x^100)*(1-x^500)),{x,0,2000}] (same command should work on Mathematica), the number you want is 86950230.$endgroup$
– achille hui
Dec 18 '18 at 23:52
$begingroup$
@MathNewbie No, sorry. This is related to "partitions" and that is a very difficult combinatorial problem. en.wikipedia.org/wiki/Partition_(number_theory)
$endgroup$
– Fly by Night
Dec 19 '18 at 0:46
$begingroup$
@MathNewbie No, sorry. This is related to "partitions" and that is a very difficult combinatorial problem. en.wikipedia.org/wiki/Partition_(number_theory)
$endgroup$
– Fly by Night
Dec 19 '18 at 0:46
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
So you have to find the number of non-negative integer solutions to:
$$a+5b+10c+20d+50e+100f+500g = 2000$$
A short C++ program with no more than 20 lines of code and a simple recurrence will serve for the purpose.
#include <iostream>
using namespace std;
int numSolutions(int *list, int size, int sum) {
int num = list[0];
if(size == 1) {
return (sum % num == 0)? 1: 0;
}
int count = 0, cases = sum / num;
for(int i = 0; i <= cases; i++) {
count += numSolutions(list + 1, size - 1, sum - i * num);
}
return count;
}
int main() {
int list = {500, 100, 50, 20, 10, 5, 1};
int size = 7, sum = 2000;
cout << numSolutions(list, size, sum);
}
...and the answer is: 86950230. Execution time is less than a second.
answered Dec 19 '18 at 11:56
OldboyOldboy
8,57511036
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add a comment |
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$begingroup$
So you have to find the number of non-negative integer solutions to:
$$a+5b+10c+20d+50e+100f+500g = 2000$$
A short C++ program with no more than 20 lines of code and a simple recurrence will serve for the purpose.
#include <iostream>
using namespace std;
int numSolutions(int *list, int size, int sum) {
int num = list[0];
if(size == 1) {
return (sum % num == 0)? 1: 0;
}
int count = 0, cases = sum / num;
for(int i = 0; i <= cases; i++) {
count += numSolutions(list + 1, size - 1, sum - i * num);
}
return count;
}
int main() {
int list = {500, 100, 50, 20, 10, 5, 1};
int size = 7, sum = 2000;
cout << numSolutions(list, size, sum);
}
...and the answer is: 86950230. Execution time is less than a second.
answered Dec 19 '18 at 11:56
OldboyOldboy
8,57511036
$endgroup$
add a comment |
$begingroup$
So you have to find the number of non-negative integer solutions to:
$$a+5b+10c+20d+50e+100f+500g = 2000$$
A short C++ program with no more than 20 lines of code and a simple recurrence will serve for the purpose.
#include <iostream>
using namespace std;
int numSolutions(int *list, int size, int sum) {
int num = list[0];
if(size == 1) {
return (sum % num == 0)? 1: 0;
}
int count = 0, cases = sum / num;
for(int i = 0; i <= cases; i++) {
count += numSolutions(list + 1, size - 1, sum - i * num);
}
return count;
}
int main() {
int list = {500, 100, 50, 20, 10, 5, 1};
int size = 7, sum = 2000;
cout << numSolutions(list, size, sum);
}
...and the answer is: 86950230. Execution time is less than a second.
answered Dec 19 '18 at 11:56
OldboyOldboy
8,57511036
$endgroup$
add a comment |
$begingroup$
So you have to find the number of non-negative integer solutions to:
$$a+5b+10c+20d+50e+100f+500g = 2000$$
A short C++ program with no more than 20 lines of code and a simple recurrence will serve for the purpose.
#include <iostream>
using namespace std;
int numSolutions(int *list, int size, int sum) {
int num = list[0];
if(size == 1) {
return (sum % num == 0)? 1: 0;
}
int count = 0, cases = sum / num;
for(int i = 0; i <= cases; i++) {
count += numSolutions(list + 1, size - 1, sum - i * num);
}
return count;
}
int main() {
int list = {500, 100, 50, 20, 10, 5, 1};
int size = 7, sum = 2000;
cout << numSolutions(list, size, sum);
}
...and the answer is: 86950230. Execution time is less than a second.
answered Dec 19 '18 at 11:56
OldboyOldboy
8,57511036
$endgroup$
So you have to find the number of non-negative integer solutions to:
$$a+5b+10c+20d+50e+100f+500g = 2000$$
A short C++ program with no more than 20 lines of code and a simple recurrence will serve for the purpose.
#include <iostream>
using namespace std;
int numSolutions(int *list, int size, int sum) {
int num = list[0];
if(size == 1) {
return (sum % num == 0)? 1: 0;
}
int count = 0, cases = sum / num;
for(int i = 0; i <= cases; i++) {
count += numSolutions(list + 1, size - 1, sum - i * num);
}
return count;
}
int main() {
int list = {500, 100, 50, 20, 10, 5, 1};
int size = 7, sum = 2000;
cout << numSolutions(list, size, sum);
}
...and the answer is: 86950230. Execution time is less than a second.
answered Dec 19 '18 at 11:56
OldboyOldboy
8,57511036
answered Dec 19 '18 at 11:56
OldboyOldboy
8,57511036
answered Dec 19 '18 at 11:56
OldboyOldboy
8,57511036
answered Dec 19 '18 at 11:56
OldboyOldboy
8,57511036
8,57511036
add a comment |
add a comment |
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$begingroup$
You need to find non-negative integer solutions to $$a+5b+10c+20d+50e+100f+500g = 2000$$
$endgroup$
– Fly by Night
Dec 18 '18 at 21:35
$begingroup$
@FlybyNight could you explain how to do that?
$endgroup$
– Math Newbie
Dec 18 '18 at 21:39
$begingroup$
You can ask WA to compute the number using command
SeriesCoefficient[ 1/((1-x)*(1-x^5)*(1-x^10)*(1-x^20)*(1-x^50)*(1-x^100)*(1-x^500)),{x,0,2000}](same command should work on Mathematica), the number you want is86950230.$endgroup$
– achille hui
Dec 18 '18 at 23:52
$begingroup$
@MathNewbie No, sorry. This is related to "partitions" and that is a very difficult combinatorial problem. en.wikipedia.org/wiki/Partition_(number_theory)
$endgroup$
– Fly by Night
Dec 19 '18 at 0:46