A006544 Number of stable forests with n nodes.
1, 1, 2, 3, 5, 8, 15, 27, 54, 110, 238, 526, 1211, 2839, 6825, 16655, 41315, 103663, 263086, 673604, 1739155, 4521632, 11831735, 31134338, 82352098, 218837877, 584018065, 1564679863, 4207224730, 11350583175, 30718054693, 83373960954, 226907180850, 619118327796
Offset: 0
Keywords
References
- N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Links
- Alois P. Heinz, Table of n, a(n) for n = 0..1000
- K. L. McAvaney, Counting stable trees, pp. 79-85 of Combinatorial Mathematics (Proceedings 2nd Australian Conf.), Lect. Notes Math. 403, 1974.
- K. L. McAvaney, Letter to N. J. A. Sloane, May 1975
Formula
G.f.: Sum_{n>=1} Z(S_n,s(x)) where s(x) is the g.f. for A003426 and Z(S_n) is the cycle index of the symmetric group on n elements. - Sean A. Irvine, Feb 13 2016
Extensions
More terms from Sean A. Irvine, Feb 13 2016