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

Author

Antti Karttunen, Nov 29 2003

Keywords

• nonn
• easy

Comments

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

Links

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

Programs

Scheme

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

Formula

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