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 A067980 #4 Mar 31 2012 13:20:07 %S A067980 3,13,31,69,140,274,519,963,1757,3165,5642,9972,17499,30521,52955, %T A067980 91461,157336,269702,460863,785295,1334713,2263293,3829846,6468264, %U A067980 10905075,18355429,30849559,51776133,86785892 %N A067980 Convolution of L(n+1) := A000204(n+1) (Lucas), n>=0, with L(n+2), n>=0. %C A067980 Second diagonal of triangle A067979. Second column of triangle A067990. %F A067980 a(n)= sum(L(k+1)*L(n+2-k), k=0..n) = (4*n+3)*F(n+1)+3*(n+1)*F(n), with F(n) := A000045(n) (Fibonacci). %F A067980 G.f.: (3+x)*(1+2*x)/(1-x-x^2)^2. %K A067980 nonn,easy %O A067980 0,1 %A A067980 _Wolfdieter Lang_, Feb 15 2002