A374493 - OEIS

A374493

Number of ways of writing n^2 as a sum of 8 squares.

1, 16, 1136, 12112, 74864, 252016, 859952, 1887888, 4793456, 8830096, 17893136, 28366288, 56672048, 77264112, 134040048, 190776112, 306783344, 386279728, 626936816, 752843856, 1179182864, 1429131216, 2014006448, 2368768912, 3628646192, 3937752016, 5485751952

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..26.

Index entries for sequences related to sums of squares

FORMULA

a(n) = [x^(n^2)] (Sum_{j=-n..n} x^(j^2))^8.

a(n) = A000143(n^2).

a(n) is divisible by 16 for n > 0.

PROG

(PARI) a000143(n) = if(n==0, 1, 16*sumdiv(n, d, (-1)^(n+d)*d^3));