A060910 E.g.f.: exp(x*exp(x*exp(x)) + 1/2*x^2*exp(x*exp(x))^2 + 1/4*x^4*exp(x*exp(x))^4).

1, 1, 4, 25, 200, 1941, 22552, 304207, 4660224, 79627609, 1496962736, 30645682299, 677868344056, 16102526543533, 408764126148120, 11042583947604871, 316299747976627808, 9574687031473970673

Offset: 0

Author

Vladeta Jovovic, Apr 07 2001

Keywords

• nonn

References

• I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983.

Crossrefs

Cf. A000949 - A000951, A060905 - A060913.

Formula

E.g.f.: exp(Sum_{d|m} T_k^d/d), where T_k = x*exp(T_(k - 1)), k >= 1, T_0 = x; k = 2, m = 4.