A000083 Number of mixed Husimi trees with n nodes; or polygonal cacti with bridges.
1, 1, 1, 2, 4, 9, 23, 63, 188, 596, 1979, 6804, 24118, 87379, 322652, 1209808, 4596158, 17657037, 68497898, 268006183, 1056597059, 4193905901, 16748682185, 67258011248, 271452424286, 1100632738565, 4481533246014, 18319020658537, 75152228262785, 309337095953934
Offset: 0
Keywords
References
- N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
- N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Links
- Christian G. Bower, Table of n, a(n) for n = 0..500
- G. W. Ford and G. E. Uhlenbeck, Combinatorial problems in the theory of graphs III, Proc. Nat. Acad. Sci. USA, 42 (1956), 529-535.
- Eric Weisstein's World of Mathematics, Cactus Graph
- Index entries for sequences related to cacti
- Index entries for sequences related to trees
Formula
G.f.: A(x) = B(x) + C(x) - B(x)*D(x), where B, C, D respectively are g.f.s of A000237, A035349, A035350. - Christian G. Bower, Nov 15 1998
Extensions
More terms from Christian G. Bower, Nov 15 1998