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 A111989 #11 Jun 13 2015 00:51:54 %S A111989 1,6,36,208,1200,6912,39808,229248,1320192,7602688,43782144,252131328, %T A111989 1451966464,8361541632,48152199168,277297463296,1596892446720, %U A111989 9196137086976,52958442815488,304975517319168,1756284007219200 %N A111989 G.f.: 1/(1-6*x+8*x^3). %D A111989 Charles Jordan, Calculus of Finite Differences, Chelsea, 1965, p. 43. See the reference to L. Euler there. %H A111989 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (6,0,-8). %F A111989 a(n)= 6*a(n-1)-8*a(n-3), a(-2)= 0 =a(-1), a(0)=1, (or a(j)=6^j, j=0, 1, 2). %Y A111989 Cf. A111990 (first convolution), A111991 (second convolution). %K A111989 nonn,easy %O A111989 0,2 %A A111989 _Wolfdieter Lang_, Sep 12 2005