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 A089873 #5 Mar 31 2012 14:02:17 %S A089873 1,1,2,2,2,4,4,4,10,6,10,12,16,20,36,28,56,46,104,84,166 %N A089873 Number of fixed points in range [A014137(n-1)..A014138(n-1)] of permutation A071665/A071666. %C A089873 The number of n-node binary trees fixed by the corresponding automorphism(s). %H A089873 A. Karttunen, <a href="/A089408/a089408.c.txt">C-program for computing the initial terms of this sequence</a> %K A089873 nonn %O A089873 0,3 %A A089873 _Antti Karttunen_, Nov 29 2003