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 A089847 #6 Mar 31 2012 14:02:17 %S A089847 1,1,2,3,8,24,72,231,764,2574,8840,30796,108528,386308,1386756, %T A089847 5014575,18249120,66786738,245642760,907513530,3366215688,12531502620, %U A089847 46805032560,175341580596,658674458208,2480584898700,9363748625972 %N A089847 Number of cycles in range [A014137(n-1)..A014138(n-1)] of permutation A089851/A089853. %C A089847 The number of orbits to which the corresponding automorphism(s) partitions the set of A000108(n) binary trees with n internal nodes. %H A089847 A. Karttunen, <a href="/A089408/a089408.c.txt">C-program for computing the initial terms of this sequence</a> %F A089847 a(n) = (1/3 * A000108(n)) + (2/3 * A089848(n)) %p A089847 A089847 := n -> (1/3)*(A000108(n)+2*A089848(n)); %o A089847 (Scheme) (define (A089847 n) (/ (+ (A000108 n) (* 2 (A089848 n))) 3)) %K A089847 nonn,easy %O A089847 0,3 %A A089847 _Antti Karttunen_, Nov 29 2003