A080972 - OEIS

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A080972

a(n) = A080969(n)/A080967(A080979(A080970(n))).

1, 1, 1, 2, 2, 2, 2, 2, 2, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 3, 1, 2, 1, 4, 1, 2, 1, 2, 2, 3, 3, 1, 2, 2, 1, 2, 4, 1, 1, 2, 1, 4, 4, 1, 2, 2, 1, 2, 4, 1, 2, 4, 2, 4, 1, 1, 4, 4, 1, 4, 1, 2, 1, 4, 4, 2, 1, 4, 4, 2, 4, 4, 2, 1

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OFFSET

0,4

COMMENTS

Donaghey shows in his paper that the orbit size (under the automorphism A057505/A057506) of each non-branch-reduced tree encoded by A080971(n) is divisible by the orbit size of the corresponding branch-reduced tree. This sequence gives the corresponding ratio.

LINKS

Table of n, a(n) for n=0..100.

Robert Donaghey, Automorphisms on Catalan trees and bracketing, J. Combin. Theory, Series B, 29 (1980), 75-90.

CROSSREFS

Sequence in context: A192227 A102673 A085297 * A037814 A179529 A118668

Adjacent sequences: A080969 A080970 A080971 * A080973 A080974 A080975

KEYWORD

nonn

AUTHOR

Antti Karttunen, Mar 02 2003

STATUS

approved