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A089847
Number of cycles in range [A014137(n-1)..A014138(n-1)] of permutation A089851/A089853.
5
1, 1, 2, 3, 8, 24, 72, 231, 764, 2574, 8840, 30796, 108528, 386308, 1386756, 5014575, 18249120, 66786738, 245642760, 907513530, 3366215688, 12531502620, 46805032560, 175341580596, 658674458208, 2480584898700, 9363748625972
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.
FORMULA
a(n) = (1/3 * A000108(n)) + (2/3 * A089848(n))
MAPLE
A089847 := n -> (1/3)*(A000108(n)+2*A089848(n));
PROG
(Scheme) (define (A089847 n) (/ (+ (A000108 n) (* 2 (A089848 n))) 3))
CROSSREFS
Sequence in context: A327009 A271269 A331874 * A304121 A038561 A055981
KEYWORD
nonn,easy
AUTHOR
Antti Karttunen, Nov 29 2003
STATUS
approved