OFFSET
0,3
REFERENCES
I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983.
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 = 4, m = 2.
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladeta Jovovic, Apr 07 2001
STATUS
approved