A007098 Number of unlabeled bisectable trees with 2n+1 nodes. (Formerly M2596)

1, 1, 3, 6, 19, 47, 140, 374, 1082, 2998, 8574, 24130, 68876, 195587, 559076, 1596651, 4575978, 13122219, 37711998, 108488765, 312577827, 901531937, 2603264050, 7524331268, 21768850808, 63032844756, 182662328945, 529722408615, 1537261773438

Offset

0,3

References

R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1980.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

R. W. Robinson, Table of n, a(n) for n = 0..99

F. Harary, R. W. Robinson, Isomorphic factorizations VIII: bisectable trees, Combinatorica 4 (2) (1984) 169-179.

Index entries for sequences related to trees

Formula

a(n) = Sum_{k=1..n} binomial(k + 1, 2) * A228601(n, k). - Sean A. Irvine, Oct 10 2017

Crossrefs

Cf. A228601.

Sequence in context: A347685 A219286 A104264 * A226322 A148566 A148567

Adjacent sequences: A007095 A007096 A007097 * A007099 A007100 A007101

Keyword

nonn

Author

N. J. A. Sloane, Mira Bernstein

Extensions

a(23) onwards added by N. J. A. Sloane, Oct 19 2006 from the Robinson reference

Status

approved