A350306 a(n) is the constant term in the expansion of Product_{k=1..n} (x^k + 1 + 1/x^k)^k.

1, 1, 3, 57, 2855, 459597, 240485241, 395649695145, 2023017357650345, 31899582278283495743, 1542718311570632349138107, 227912729019868361872929934159, 102547791095886594007005283976727239, 140202209701199998336689204011032887220183

Offset: 0

Author

Seiichi Manyama, Dec 23 2021

Keywords

• nonn

Crossrefs

Cf. A350283, A350305, A350308.

Programs

Mathematica

a[n_] := Coefficient[Series[Product[(x^k + 1 + 1/x^k)^k, {k, 1, n}], {x, 0, 0}], x, 0]; Array[a, 14, 0] (* Amiram Eldar, Dec 24 2021 *)

PARI

a(n) = polcoef(prod(k=1, n, (x^k+1+1/x^k)^k), 0);