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 A089880 #6 Mar 31 2012 14:02:18 %S A089880 1,1,2,3,10,22,76,217,750,2438,8524,29414,104468,371516,1338936, %T A089880 4847637,17685270,64823110,238843660,883634026,3282152588,12233141908, %U A089880 45741634536,171529836218,644953425740,2430973304732,9183681736376 %N A089880 Number of cycles in range [A014137(n-1)..A014138(n-1)] of permutation A069772. %C A089880 The number of orbits to which the corresponding automorphism(s) partitions the set of A000108(n) binary trees with n internal nodes. %H A089880 A. Karttunen, <a href="/A089408/a089408.c.txt">C-program for computing the initial terms of this sequence</a> %F A089880 a(n) = (A000108(n)+A089849(n))/2 %o A089880 (Scheme) (define (A089880 n) (/ (+ (A000108 n) (A089849 n)) 2)) %K A089880 nonn,easy %O A089880 0,3 %A A089880 _Antti Karttunen_, Nov 29 2003