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A298938 Number of ordered ways of writing n^3 as a sum of n squares of nonnegative integers. 3
1, 1, 1, 4, 5, 686, 13942, 455988, 13617853, 454222894, 18323165948, 802161109047, 42149084452070, 2481730049781672, 157265294178424356, 10977302934685469078, 812821237985857557677, 64539935903231450294134, 5504599828399250884049308 (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>=0} x^(k^2))^n.

EXAMPLE

a(4) = 5 because we have [64, 0, 0, 0], [16, 16, 16, 16], [0, 64, 0, 0], [0, 0, 64, 0] and [0, 0, 0, 64].

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, A298936, A298939.

Sequence in context: A042717 A304286 A134463 * A309071 A270975 A058916

Adjacent sequences:  A298935 A298936 A298937 * A298939 A298940 A298941

KEYWORD

nonn

AUTHOR

Ilya Gutkovskiy, Jan 29 2018

STATUS

approved

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Last modified February 17 23:35 EST 2020. Contains 332006 sequences. (Running on oeis4.)