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A000237
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Number of mixed Husimi trees with n nodes; or rooted polygonal cacti with bridges.
(Formerly M2754 N1107)
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12
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0, 1, 1, 3, 8, 26, 84, 297, 1066, 3976, 15093, 58426, 229189, 910127, 3649165, 14756491, 60103220, 246357081, 1015406251, 4205873378, 17497745509, 73084575666, 306352303774, 1288328048865, 5433980577776, 22982025183983
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,4
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REFERENCES
| G. W. Ford and G. E. Uhlenbeck, Combinatorial problems in the theory of graphs III, Proc. Nat. Acad. Sci. USA, 42 (1956), 529-535.
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).
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LINKS
| Christian G. Bower, Table of n, a(n) for n=0..500
C. G. Bower, Transforms (2)
N. J. A. Sloane, Transforms
Index entries for sequences related to cacti
Index entries for sequences related to rooted trees
Index entries for sequences related to trees
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FORMULA
| Shifts left under transform T where Ta = EULER(BIK(a)). [See Transforms links.]
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CROSSREFS
| Cf. A000083, A000314, A035082, A035349-A035357.
Sequence in context: A148803 A148804 A148805 * A148806 A148807 A148808
Adjacent sequences: A000234 A000235 A000236 * A000238 A000239 A000240
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KEYWORD
| nonn,eigen,nice,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| More terms and formula from Christian G. Bower (bowerc(AT)usa.net), Nov 15 1998
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