login

Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.

a(n) = [x^(n^2)] Product_{k=1..n} (x^(k^2) + 1 + 1/x^(k^2)).
2

%I #5 Jan 23 2024 08:40:58

%S 1,1,1,1,1,2,5,13,31,75,155,344,808,2019,5136,13422,34720,91055,

%T 238447,630753,1678780,4502862,12135507,32873145,89324119,243745113,

%U 667153916,1832553339,5048767393,13950607375,38649239592,107345311219,298820158401,833680894927

%N a(n) = [x^(n^2)] Product_{k=1..n} (x^(k^2) + 1 + 1/x^(k^2)).

%t Table[Coefficient[Product[(x^(k^2) + 1 + 1/x^(k^2)), {k, 1, n}], x, n^2], {n, 0, 33}]

%Y Cf. A000290, A316706, A350249, A368243.

%K nonn

%O 0,6

%A _Ilya Gutkovskiy_, Jan 23 2024