A050398 Exponential reversion of sequence of involutions (A000085).

1, -2, 8, -50, 434, -4864, 66996, -1095324, 20724756, -445310616, 10708301328, -284863999848, 8304979127496, -263299784899488, 9018495674420592, -331867682445078000, 13057137391032043920, -546957850901539335840

Offset: 1

Author

Christian G. Bower, Nov 15 1999

Keywords

• sign

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..200
• N. J. A. Sloane, Transforms
• Index entries for reversions of series

Crossrefs

Cf. A000085, A050397.

Programs

PARI

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

Formula

E.g.f. A(x) satisfies: A(x) = log(1 + x) - A(x)^2/2. - Ilya Gutkovskiy, Apr 23 2020