A089402 Number of cycles in range [A014137(n-1)..A014138(n-1)] of permutation A089864.

1, 1, 2, 3, 8, 22, 68, 217, 720, 2438, 8412, 29414, 104048, 371516, 1337352, 4847637, 17679264, 64823110, 238820780, 883634026, 3282065072, 12233141908, 45741298616, 171529836218, 644952132448, 2430973304732, 9183676744088

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) = (A000108(n)+A089408(n))/2

Prog

(Scheme) (define (A089402 n) (* (/ 1 2) (+ (A000108 n) (A089408 n))))

Crossrefs

Sequence in context: A098119 A049959 A006545 * A127940 A006796 A241904

Adjacent sequences: A089399 A089400 A089401 * A089403 A089404 A089405

Keyword

nonn,easy

Author

Antti Karttunen, Nov 29 2003

Status

approved