This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A123694 #5 Mar 31 2012 14:02:29 %S A123694 0,7,91,92,93,94,95,114,115,116,117,118,4207,4209,4211,4214,4216,4299, %T A123694 4301,4303,4305,4307,1228,1229,1230,1231,1232,1233,1234,1235,1236, %U A123694 1237,1238,1239,1240,1241,1242,1243,1244,1245,1246,1247,1248,1249,1250,1347 %N 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. %C A123694 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. %H A123694 A. Karttunen, <a href="/A089839/a089839.c.txt">C-program for computing the initial terms of this sequence</a> %H A123694 A. Karttunen, <a href="/A089840/a089840p.txt">Prolog-program which illustrates the nonrecursive Catalan automorphisms given on example-lines.</a> %e A123694 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. %K A123694 nonn %O A123694 0,2 %A A123694 _Antti Karttunen_, Oct 11 2006