A050397 Reversion of sequence of involutions (A000085).

1, -2, 4, -10, 30, -104, 392, -1568, 6520, -27976, 122944, -551680, 2518912, -11684000, 54957216, -261897024, 1263216192, -6164172608, 30416619200, -151750104800, 765364073120, -3902783995520, 20123276097920

Offset

1,2

Links

Andrew Howroyd, Table of n, a(n) for n = 1..200

N. J. A. Sloane, Transforms

Index entries for reversions of series

Maple

# Using function CompInv from A357588.
CompInv(23, n -> simplify(hypergeom([-n/2, (1-n)/2], [], 2))); # Peter Luschny, Oct 05 2022

Prog

(PARI) seq(n)=Vec(serreverse(serlaplace(-1 + exp(x+x^2/2 + O(x*x^n))))) \\ Andrew Howroyd, May 06 2023

Crossrefs

Cf. A000085, A050398.

Sequence in context: A274232 A360322 A112846 * A186021 A332650 A091174

Adjacent sequences: A050394 A050395 A050396 * A050398 A050399 A050400

Keyword

sign

Author

Christian G. Bower, Nov 15 1999

Status

approved