A089880 Number of cycles in range [A014137(n-1)..A014138(n-1)] of permutation A069772.

1, 1, 2, 3, 10, 22, 76, 217, 750, 2438, 8524, 29414, 104468, 371516, 1338936, 4847637, 17685270, 64823110, 238843660, 883634026, 3282152588, 12233141908, 45741634536, 171529836218, 644953425740, 2430973304732, 9183681736376

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)+A089849(n))/2

Prog

(Scheme) (define (A089880 n) (/ (+ (A000108 n) (A089849 n)) 2))

Crossrefs

Sequence in context: A148057 A148058 A148059 * A271740 A130002 A320812

Adjacent sequences: A089877 A089878 A089879 * A089881 A089882 A089883

Keyword

nonn,easy

Author

Antti Karttunen, Nov 29 2003

Status

approved