A298939 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

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

(list; graph; refs; listen; history; text; internal format)

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