OFFSET
0,9
FORMULA
a(n) = [x^(n^2)] Product_{k=1..n} (x^(k^2) + 1/x^(k^2)).
MAPLE
b:= proc(n, i) option remember; (m-> `if`(n>m, 0, `if`(n=m, 1,
b(abs(n-i^2), i-1) +b(n+i^2, i-1))))((1+(3+2*i)*i)*i/6)
end:
a:= n-> `if`(irem(n, 4)>1, 0, b(n^2, n)):
seq(a(n), n=0..49); # Alois P. Heinz, Jan 22 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Jan 22 2024
STATUS
approved