A129607 - OEIS

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A129607

Signature-permutation of a Catalan automorphism: swap the left and right subtree of degree 2 general trees.

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, 28, 29, 30, 44, 47, 33, 53, 56, 60, 37, 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

Otherwise like automorphism *A072796, except that this involution exchanges the two leftmost subtrees of a general tree ONLY when the degree of the tree is two. Automorphism *A129608 = SPINE(*A129607) = ENIPS(*A129607). See the definitions given in A122203 and A122204.

LINKS

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

A. Karttunen, Prolog-program which illustrates the construction of this and similar nonrecursive Catalan automorphisms.

Index entries for signature-permutations of Catalan automorphisms

PROG

(Constructive and destructive Scheme implementation of this automorphism. These act on S-expressions, i.e. list-structures:)

(define (*A129607 s) (if (= 2 (length s)) (*A072796 s) s))

(define (*A129607! s) (if (= 2 (length s)) (*A072796! s)) s)

CROSSREFS

Row 3608 of A089840.

Sequence in context: A227788 A222245 A275582 * A130340 A130339 A350348

Adjacent sequences: A129604 A129605 A129606 * A129608 A129609 A129610

KEYWORD

nonn

AUTHOR

Antti Karttunen, May 22 2007

STATUS

approved