OFFSET
0,5
COMMENTS
a(n) is the number of representations of n as a sum of n squares of nonnegative integers.
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..500
FORMULA
a(n) = [x^n] (1 + theta_3(x))^n/2^n, where theta_() is the Jacobi theta function. - Ilya Gutkovskiy, Jan 17 2018
a(n) ~ c * d^n / sqrt(n), where d = 2.83312434251238... and c = 0.229098651125... - Vaclav Kotesovec, Mar 25 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, May 28 2017
STATUS
approved