A298939 Number of ordered ways of writing n^3 as a sum of n squares of positive integers.

1, 1, 1, 4, 1, 286, 7582, 202028, 6473625, 226029577, 8338249868, 391526193477, 19990594900630, 1159906506684446, 74890158861242740, 5119732406649036418, 380146984328280974281, 30198665638519565614034, 2555354508318427693497565

Offset

0,4

Links

Table of n, a(n) for n=0..18.

Index entries for sequences related to sums of squares

Formula

a(n) = [x^(n^3)] (Sum_{k>=1} x^(k^2))^n.

Example

a(3) = 4 because we have [25, 1, 1], [9, 9, 9], [1, 25, 1] and [1, 1, 25].

Mathematica

Table[SeriesCoefficient[(-1 + EllipticTheta[3, 0, x])^n/2^n, {x, 0, n^3}], {n, 0, 18}]

Crossrefs

Cf. A000290, A000578, A006456, A030273, A037444, A066535, A218494, A232173, A287617, A298329, A298330, A298935, A298937, A298938.

Sequence in context: A299522 A300140 A347554 * A240098 A094337 A345313

Adjacent sequences: A298936 A298937 A298938 * A298940 A298941 A298942

Keyword

nonn

Author

Ilya Gutkovskiy, Jan 29 2018

Status

approved