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 A089407 #6 Mar 31 2012 14:02:17 %S A089407 1,1,1,2,4,11,34,109,360,1219,4206,14708,52024,185758,668676,2423821, %T A089407 8839632,32411555,119410390,441817020,1641032536,6116570954, %U A089407 22870649308,85764918130,322476066224,1215486652366,4591838372044,17383387914792 %N A089407 Number of cycles in range [A014137(n-1)..A014138(n-1)] of permutation A089859/A089863. %C A089407 The number of orbits to which the corresponding automorphism(s) partitions the set of A000108(n) binary trees with n internal nodes. %H A089407 A. Karttunen, <a href="/A089408/a089408.c.txt">C-program for computing the initial terms of this sequence</a> %F A089407 a(0) = a(1) = 1, a(n) = (1/4)*(A000108(n) + A089408(n) + (if (n == 3 mod 4) 2*A000108((n-3)/4))) %o A089407 (Scheme) (define (A089407 n) (if (< n 2) 1 (* (/ 1 4) (+ (A000108 n) (A089408 n) (if (= 3 (modulo n 4)) (* 2 (A000108 (/ (- n 3) 4))) 0))))) %K A089407 nonn,easy %O A089407 0,4 %A A089407 _Antti Karttunen_, Nov 29 2003