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A374493
Number of ways of writing n^2 as a sum of 8 squares.
0
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
OFFSET
0,2
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));
a(n) = a000143(n^2);
CROSSREFS
Column k=8 of A302996.
Cf. A000143.
Sequence in context: A265622 A144915 A209541 * A279295 A353029 A053903
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jul 12 2024
STATUS
approved