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Search: id:A000673
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| A000673 |
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Number of bicentered 3-valent (or boron, or binary) trees with n nodes.
(Formerly M0355 N0133)
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+0
3
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| 0, 0, 1, 0, 1, 1, 2, 2, 6, 8, 18, 30, 67, 127, 275, 551, 1192, 2507, 5475, 11820, 26007, 57077, 126686, 281625, 630660, 1416116, 3195784, 7232624, 16430563, 37429146, 85528079, 195940960, 450074270, 1036226173, 2391193488, 5529420585
(list; graph; listen)
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OFFSET
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0,7
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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).
A. Cayley, On the analytical forms called trees, with application to the theory of chemical combinations, Reports British Assoc. Advance. Sci. 45 (1875), 257-305 = Math. Papers, Vol. 9, 427-460 (see p. 451).
R. C. Read, personal communication.
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LINKS
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E. M. Rains and N. J. A. Sloane, On Cayley's Enumeration of Alkanes (or 4-Valent Trees)., J. Integer Sequences, Vol. 2 (1999), Article 99.1.1.
Index entries for sequences related to trees
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CROSSREFS
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A000672 = A000673 + A000675. Cf. A000022, A000200, A000602.
Sequence in context: A033760 A136513 A054153 this_sequence A129383 A052957 A157253
Adjacent sequences: A000670 A000671 A000672 this_sequence A000674 A000675 A000676
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KEYWORD
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nonn,easy,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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