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A000677 Number of bicentered trees with n nodes.
(Formerly M2366 N0936)
+0
6
0, 0, 1, 0, 1, 1, 3, 4, 11, 20, 51, 108, 267, 619, 1541, 3762, 9497, 23907, 61216, 157211, 407919, 1063398, 2792026, 7365532, 19535887, 52037837, 139213244, 373820978, 1007420841, 2723783122, 7387129661, 20091790330, 54793762295 (list; graph; listen)
OFFSET

0,7

COMMENT

See A000676 for more information.

REFERENCES

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).

N. L. Biggs et al., Graph Theory 1736-1936, Oxford, 1976, p. 49.

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. 438).

LINKS

N. J. A. Sloane, Table of n, a(n) for n = 0..200

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.

N. J. A. Sloane, Maple program

Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.

Index entries for sequences related to trees

MAPLE

See link for Maple program.

CROSSREFS

A000676+A000677 = A000055.

Sequence in context: A036652 A097072 A049977 this_sequence A110865 A152982 A001642

Adjacent sequences: A000674 A000675 A000676 this_sequence A000678 A000679 A000680

KEYWORD

nonn,easy,nice

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

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Last modified December 17 19:39 EST 2009. Contains 170821 sequences.


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