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A080973 A014486-encoding of the "Moose trees". 10
2, 52, 14952, 4007632, 268874213792, 68836555442592, 4561331969745081152, 300550070677246403229312, 1294530259719904904564091957759232, 331402554328705507772604330809117952 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Meeussen's observation about the orbits of a composition of two involutions F and R states that if the orbit size of the composition (acting on a particular element of the set) is odd, then it contains an element fixed by the other involution if and only if it contains also an element fixed by the other, on the (almost) opposite side of the cycle. Here those two involutions are A057163 and A057164, their composition is Donaghey's "Map M" A057505 and as the trees A080293/A080295 are symmetric as binary trees and the cycle sizes A080292 are odd, it follows that these are symmetric as general trees.

LINKS

Table of n, a(n) for n=0..9.

A. Karttunen, Initial terms illustrated

FORMULA

a(n) = A014486(A080975(n)) = A014486(A057505^((A080292(n)+1)/2) (A080293(n))) [where ^ stands for the repeated applications of permutation A057505.]

CROSSREFS

Same sequence in binary: A080974. A036044(a(n)) = a(n) for all n. The number of edges (as general trees): A080978.

Sequence in context: A121293 A246743 A057106 * A230882 A216354 A079179

Adjacent sequences:  A080970 A080971 A080972 * A080974 A080975 A080976

KEYWORD

nonn

AUTHOR

Antti Karttunen Mar 02 2003

STATUS

approved

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Last modified August 21 18:26 EDT 2019. Contains 326168 sequences. (Running on oeis4.)