A303613 a(n) = [x^n] (1/6 * Sum_{k=0..n} (k+3)!*x^k)^(1/2).

1, 2, 8, 44, 300, 2408, 22056, 225824, 2547352, 31322640, 416442016, 5948450912, 90815006528, 1475513165184, 25419300628160, 462839142264960, 8882065110092000, 179190173518717120, 3791700201187720960, 83977684252758211200, 1942984028971973710720

Offset: 0

Author

Seiichi Manyama, Apr 27 2018

Keywords

• nonn

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..447

Crossrefs

Cf. A001715, A303568.

Programs

PARI

N=66; x='x+O('x^N); Vec((1/3!*sum(k=0, N, (k+3)!*x^k))^(1/2))