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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

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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 A383503 A389062

Adjacent sequences: A089877 A089878 A089879 * A089881 A089882 A089883

KEYWORD

nonn,easy

AUTHOR

Antti Karttunen, Nov 29 2003

STATUS

approved

URL: https://oeis.org/A089880

⇱ A089880 - OEIS