A055403 Number of points in N^4 of norm <= n.

1, 5, 20, 70, 165, 357, 688, 1154, 1867, 2907, 4272, 6070, 8357, 11307, 14998, 19470, 24809, 31211, 38928, 47816, 58201, 70361, 83962, 99648, 117519, 137521, 160270, 185528, 213615, 244649, 279370, 317006, 358809, 404823, 454838, 509486, 568493

Offset: 0

Author

David W. Wilson

Keywords

• nonn

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..500

Crossrefs

Column k=4 of A302998.

Formula

a(n) = [x^(n^2)] (1 + theta_3(x))^4/(16*(1 - x)), where theta_3() is the Jacobi theta function. - Ilya Gutkovskiy, Apr 15 2018