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A000673 Number of bicentered 3-valent (or boron, or binary) trees with n nodes.
(Formerly M0355 N0133)
+0
3
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)
OFFSET

0,7

REFERENCES

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.

LINKS

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

CROSSREFS

A000672 = A000673 + A000675. Cf. A000022, A000200, A000602.

Sequence in context: A033760 A136513 A054153 this_sequence A129383 A052957 A074933

Adjacent sequences: A000670 A000671 A000672 this_sequence A000674 A000675 A000676

KEYWORD

nonn,easy,nice

AUTHOR

njas

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Last modified July 25 07:41 EDT 2008. Contains 142293 sequences.


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