A089847 Number of cycles in range [A014137(n-1)..A014138(n-1)] of permutation A089851/A089853.

1, 1, 2, 3, 8, 24, 72, 231, 764, 2574, 8840, 30796, 108528, 386308, 1386756, 5014575, 18249120, 66786738, 245642760, 907513530, 3366215688, 12531502620, 46805032560, 175341580596, 658674458208, 2480584898700, 9363748625972

Offset

0,3

Comments

The number of orbits to which the corresponding automorphism(s) partitions the set of A000108(n) binary trees with n internal nodes.

Links

Table of n, a(n) for n=0..26.

A. Karttunen, C-program for computing the initial terms of this sequence

Formula

a(n) = (1/3 * A000108(n)) + (2/3 * A089848(n))

Maple

A089847 := n -> (1/3)*(A000108(n)+2*A089848(n));

Prog

(Scheme) (define (A089847 n) (/ (+ (A000108 n) (* 2 (A089848 n))) 3))

Crossrefs

Sequence in context: A327009 A271269 A331874 * A304121 A038561 A055981

Adjacent sequences: A089844 A089845 A089846 * A089848 A089849 A089850

Keyword

nonn,easy

Author

Antti Karttunen, Nov 29 2003

Status

approved