A123694 - OEIS

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A123694

a(n) gives the A089840-index of the nonrecursive Catalan automorphism which is formed from A089840[n] by applying it to the left subtree of a binary tree and leaving the right-hand side subtree intact.

0, 7, 91, 92, 93, 94, 95, 114, 115, 116, 117, 118, 4207, 4209, 4211, 4214, 4216, 4299, 4301, 4303, 4305, 4307, 1228, 1229, 1230, 1231, 1232, 1233, 1234, 1235, 1236, 1237, 1238, 1239, 1240, 1241, 1242, 1243, 1244, 1245, 1246, 1247, 1248, 1249, 1250, 1347

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OFFSET

0,2

COMMENTS

If the count of fixed points of the automorphism A089840[n] is given by sequence f, then the count of fixed points of the automorphism A089840[A123694(n)] is given by CONV(f,A000108) (where CONV stands for convolution). See also the comments at A122200.

LINKS

Table of n, a(n) for n=0..45.

A. Karttunen, C-program for computing the initial terms of this sequence

A. Karttunen, Prolog-program which illustrates the nonrecursive Catalan automorphisms given on example-lines.

EXAMPLE

When A089840[1] = A069770 (swap binary tree sides) is applied to the left subtree of a binary tree, we get A089840[7] = A089854, thus a(1)=7. When A089840[12] = A074679 is applied to the left subtree of a binary tree, we get A089840[4207] = A089865, thus a(12)=4207.

CROSSREFS

Sequence in context: A306137 A226624 A266236 * A319978 A085026 A221132

Adjacent sequences: A123691 A123692 A123693 * A123695 A123696 A123697

KEYWORD

nonn

AUTHOR

Antti Karttunen, Oct 11 2006

STATUS

approved