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 A087159 #5 Mar 30 2012 18:36:38 %S A087159 1,2,2,3,2,2,3,2,2,4,2,2,2,3,2,2,3,2,2,4,2,2,2,3,2,2,3,2,2,5,2,2,2,2, %T A087159 3,2,2,3,2,2,3,2,2,4,2,2,2,3,2,2,3,2,2,4,2,2,2,3,2,2,3,2,2,5,2,2,2,2, %U A087159 3,2,2,3,2,2,3,2,2,4,2,2,2,3,2,2,3,2,2,4,2,2,2,3,2,2,3,2,2,6,2,2,2,2,2,3,2 %N A087159 Satisfies a(1)=1, a(A087160(n+1)) = a(n)+1, with a(m)=2 for all m not found in A087160, where A087160(n+2)=A087160(n+1)+a(n)+1. %C A087159 Records form A087161: a(A087161(n))=n and satisfy recurrence: A087161(n+3) = 5*A087161(n+2) - 6*A087161(n+1) + 2*A087161(n). %e A087159 Initialize all terms to 2. Set a(1)=1, go one term forward, %e A087159 set a(2)=a(1)+1=2, go 2 terms forward, %e A087159 set a(4)=a(2)+1=3, go 3 terms forward, %e A087159 set a(7)=a(3)+1=3, go 3 terms forward, %e A087159 set a(10)=a(4)+1=4, go 4 terms forward, %e A087159 set a(14)=a(5)+1=3, etc. %e A087159 The indices 1,2,4,7,10,14,... form A087160. %Y A087159 Cf. A087160, A087161. %K A087159 nonn %O A087159 1,2 %A A087159 _Paul D. Hanna_, Aug 22 2003