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 A298938 Number of ordered ways of writing n^3 as a sum of n squares of nonnegative integers. 3

%I

%S 1,1,1,4,5,686,13942,455988,13617853,454222894,18323165948,

%T 802161109047,42149084452070,2481730049781672,157265294178424356,

%U 10977302934685469078,812821237985857557677,64539935903231450294134,5504599828399250884049308

%N Number of ordered ways of writing n^3 as a sum of n squares of nonnegative integers.

%H <a href="/index/Su#ssq">Index entries for sequences related to sums of squares</a>

%F a(n) = [x^(n^3)] (Sum_{k>=0} x^(k^2))^n.

%e 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].

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

%Y Cf. A000290, A000578, A006456, A030273, A037444, A066535, A218494, A232173, A287617, A298329, A298330, A298935, A298936, A298939.

%K nonn

%O 0,4

%A _Ilya Gutkovskiy_, Jan 29 2018

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Last modified March 31 03:48 EDT 2020. Contains 333136 sequences. (Running on oeis4.)