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

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

Formula

a(n) = (A000108(n)+A089849(n))/2