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 A187117 #7 Mar 30 2012 18:37:26
%S A187117 1,6,39,318,3242,40348,598083,10337402,204706486,4577520108,
%T A187117 114208773268,3147671423964,95023271024164,3119560618275648,
%U A187117 110684959354534001,4221624141483353436,172274971776090819870
%N A187117 A diagonal of triangle A187115.
%C A187117 Definition of triangle: A187115(n,k) = [y^k] R_{n-1}(y+y^2) for k=2..n, n>2, where R_n(y) is the n-th row polynomial with R_2(y)=y^2.
%F A187117 Equals column 1 in the matrix cube of triangle A135080.
%o A187117 (PARI) {a(n)=local(Rn=y^2);for(m=2,n+2,Rn=subst(truncate(Rn),y,y+y^2+O(y^m)));polcoeff(Rn,n,y)}
%Y A187117 Cf. A187115, A135082, A187116, A187118, A187119.
%K A187117 nonn
%O A187117 2,2
%A A187117 _Paul D. Hanna_, Mar 08 2011