A081624 Number of 8-level labeled rooted trees with n leaves.

1, 1, 8, 92, 1380, 25488, 558426, 14140722, 406005804, 13024655442, 461451524934, 17886290630832, 752602671853068, 34152212772528222, 1662095923363838817, 86335146917372644026, 4766427291743224251474, 278658370977555551901990

Offset

0,3

References

J. Ginsburg, Iterated exponentials, Scripta Math., 11 (1945), 340-353.

T. Hogg and B. A. Huberman, Attractors on finite sets: the dissipative dynamics of computing structures, Phys. Review A 32 (1985), 2338-2346.

Links

Alois P. Heinz, Table of n, a(n) for n = 0..150

Formula

E.g.f.: exp(exp(exp(exp(exp(exp(exp(exp(x)-1)-1)-1)-1)-1)-1)-1).

Prog

(PARI) a(n)=local(X); if(n<0, 0, X=x+x*O(x^n); n!*polcoeff(exp(exp(exp(exp(exp(exp(exp(exp(X)-1)-1)-1)-1)-1)-1)-1), n))

Crossrefs

Cf. A000110, A000258, A000307, A000357, A001669.

Column k=7 of A144150.

Sequence in context: A255520 A305967 A113353 * A298188 A299083 A184142

Adjacent sequences: A081621 A081622 A081623 * A081625 A081626 A081627

Keyword

nonn

Author

Benoit Cloitre, Apr 23 2003

Status

approved