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Search: id:A000314
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| A000314 |
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Number of mixed Husimi trees with n nodes; or labeled polygonal cacti with bridges.
(Formerly M3639 N1480)
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+0
12
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| 1, 1, 1, 4, 31, 362, 5676, 111982, 2666392, 74433564, 2384579440, 86248530296, 3476794472064, 154579941792256, 7514932528712896, 396595845237540600
(list; graph; listen)
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OFFSET
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0,4
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
G. W. Ford and G. E. Uhlenbeck, Combinatorial problems in the theory of graphs III, Proc. Nat. Acad. Sci. USA, 42 (1956), 529-535.
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LINKS
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Alois P. Heinz, Table of n, a(n) for n = 0..100
Index entries for sequences related to cacti
Index entries for sequences related to trees
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FORMULA
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A035351/n, n>0.
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MAPLE
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A:= proc(n) option remember; if n<=0 then x else convert (series (x* exp ((2*A(n-1) -A(n-1)^2)/ (2-2*A(n-1))), x=0, n+2), polynom) fi end: a:= n-> if n=0 then 1 else coeff (series (A(n-1), x=0, n+1), x, n)*(n-1)! fi: seq (a(n), n=0..30); [From Alois P. Heinz (heinz(AT)hs-heilbronn.de), Aug 20 2008]
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CROSSREFS
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Cf. A000083, A000237, A035082, A035349-A035357.
Sequence in context: A145561 A086677 A016036 this_sequence A128709 A138860 A145087
Adjacent sequences: A000311 A000312 A000313 this_sequence A000315 A000316 A000317
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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More terms and formula from Christian G. Bower (bowerc(AT)usa.net), Nov 15 1998
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