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 A091233 #6 Mar 31 2012 14:02:20 %S A091233 1,1,2,4,11,53,307,2177,19503,219489,3041937,50727755,997525229, %T A091233 22742733167,592821131015,17461204518199 %N A091233 (Largest Matula-Goebel number encoding a tree with n nodes) - (smallest Matula-Goebel number encoding a tree with n nodes). %D A091233 F. Goebel, On a 1-1-correspondence between rooted trees and natural numbers, J. Combin. Theory, B 29 (1980), 141-143. %D A091233 D. Matula, A natural rooted tree enumeration by prime factorization, SIAM Rev. 10 (1968). %H A091233 A. Karttunen, <a href="/A091247/a091247.scm.txt">Scheme-program for computing this sequence.</a> %F A091233 a(n) = (A005518(n)-A005517(n))+1. %Y A091233 Compare to A091241 and A000081. Cf. A061773. %K A091233 nonn %O A091233 1,3 %A A091233 _Antti Karttunen_, Jan 03 2004