A292778 INVERT transform of double factorials.

1, 1, 3, 8, 25, 73, 234, 717, 2357, 7480, 25289, 82837, 289518, 980017, 3566993, 12526980, 47916421, 175536777, 712276698, 2736099789, 11863097885, 47932689416, 222692658177, 946323358837, 4700880455462, 20946375415505, 110626016074953, 514550968010964

Offset

0,3

Links

Alois P. Heinz, Table of n, a(n) for n = 0..807

Formula

G.f.: 1 / (1 - Sum_{k>=1} k!! * x^k). - Ilya Gutkovskiy, Dec 14 2019

Maple

a:= proc(n) option remember; `if`(n=0, 1,
      add(doublefactorial(j)*a(n-j), j=1..n))
    end:
seq(a(n), n=0..30);

Crossrefs

Cf. A006882, A051296.

Sequence in context: A213439 A006177 A148788 * A022553 A292884 A148789

Adjacent sequences: A292775 A292776 A292777 * A292779 A292780 A292781

Keyword

nonn

Author

Alois P. Heinz, Sep 22 2017

Status

approved