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 A067981 #4 Mar 31 2012 13:20:07 %S A067981 4,19,48,107,220,432,822,1529,2796,5045,9006,15936,27992,48863,84840, %T A067981 146623,252368,432816,739914,1261285,2144484,3637609,6157218,10401792, %U A067981 17541100,29531947,49644192,83336339 %N A067981 Convolution of L(n+1) := A000204(n+1) (Lucas), n>=0, with L(n+3), n>=0. %C A067981 Third diagonal of triangle A067979. Third column of triangle A067990. %F A067981 a(n)= sum(L(k+1)*L(n+3-k), k=0..n) = (7*n+4)*F(n+1)+4*(n+1)*F(n), with F(n) := A000045(n) (Fibonacci). %F A067981 G.f.: (4+3*x)*(1+2*x)/(1-x-x^2)^2. %K A067981 nonn,easy %O A067981 0,1 %A A067981 _Wolfdieter Lang_, Feb 15 2002