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A130340 Signature permutation of a Catalan automorphism: swap the two leftmost subtrees of general trees, if the root degree (A057515(n)) is even. 3
0, 1, 2, 3, 4, 6, 5, 7, 8, 9, 10, 11, 16, 19, 14, 15, 12, 17, 18, 13, 20, 21, 22, 23, 24, 25, 26, 27, 37, 29, 30, 44, 47, 33, 53, 56, 60, 28, 38, 39, 43, 52, 42, 40, 31, 45, 46, 32, 48, 49, 50, 51, 41, 34, 54, 55, 35, 57, 58, 59, 36, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

This is a self-inverse automorfism (an involution). Can be used to construct A130373.

LINKS

A. Karttunen, Table of n, a(n) for n = 0..2055

Index entries for signature-permutations of Catalan automorphisms

PROG

(Destructive Scheme implementation of this automorphism, which acts on S-expressions, i.e. list-structures:)

(define (*A130340! s) (if (even? (length s)) (*A072796! s)) s)

CROSSREFS

Cf. a(n) = A057508(A130339(A057508(n))) = A057164(A130339(A057164(n))). a(n) = A072796(n), if A057515(n) mod 2 = 0, otherwise a(n)=n.

Sequence in context: A222245 A275582 A129607 * A130339 A058812 A320454

Adjacent sequences:  A130337 A130338 A130339 * A130341 A130342 A130343

KEYWORD

nonn

AUTHOR

Antti Karttunen, Jun 05 2007

STATUS

approved

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Last modified January 21 17:07 EST 2019. Contains 319350 sequences. (Running on oeis4.)