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A089407 Number of cycles in range [A014137(n-1)..A014138(n-1)] of permutation A089859/A089863. 3
1, 1, 1, 2, 4, 11, 34, 109, 360, 1219, 4206, 14708, 52024, 185758, 668676, 2423821, 8839632, 32411555, 119410390, 441817020, 1641032536, 6116570954, 22870649308, 85764918130, 322476066224, 1215486652366, 4591838372044, 17383387914792 (list; graph; refs; listen; history; internal format)
OFFSET

0,4

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

FORMULA

a(0) = a(1) = 1, a(n) = (1/4)*(A000108(n) + A089408(n) + (if (n == 3 mod 4) 2*A000108((n-3)/4)))

PROG

(Scheme) (define (A089407 n) (if (< n 2) 1 (* (/ 1 4) (+ (A000108 n) (A089408 n) (if (= 3 (modulo n 4)) (* 2 (A000108 (/ (- n 3) 4))) 0)))))

CROSSREFS

Sequence in context: A076316 A082104 A099215 * A071115 A156809 A076317

Adjacent sequences:  A089404 A089405 A089406 * A089408 A089409 A089410

KEYWORD

nonn,easy

AUTHOR

Antti Karttunen (His_Firstname.His_Surname(AT)iki.fi), Nov 29 2003

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Last modified February 16 16:51 EST 2012. Contains 205938 sequences.