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A321435
Expansion of Product_{1 <= i <= j} (1 + x^(i^2 + j^2)).
5
1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 2, 0, 1, 2, 0, 3, 0, 2, 3, 1, 4, 1, 2, 4, 1, 6, 3, 4, 6, 2, 7, 5, 6, 8, 5, 9, 7, 9, 10, 9, 12, 10, 13, 14, 13, 18, 13, 19, 17, 18, 25, 19, 28, 24, 25, 33, 26, 36, 35, 33, 46, 35, 47, 48, 44, 61, 48, 62, 65, 60, 78, 68, 79, 87, 79, 101, 93
OFFSET
0,11
LINKS
FORMULA
G.f.: Product_{k>0} (1 + x^k)^A025426(k).
MAPLE
N:= 100: # for a(0)..a(N)
P:= 1:
for i from 1 to floor(sqrt(N)) do
for j from i while i^2 + j^2 <= N do
P:= P * (1 + x^(i^2 + j^2))
od od:
S:= series(P, x, N+1):
seq(coeff(S, x, k), k=0..N); # Robert Israel, Apr 21 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Nov 09 2018
STATUS
approved