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 A122910 #11 Jun 13 2015 00:52:09
%S A122910 1,4,45,302,2636,20184,165040,1305952,10504896,83809664,671394560,
%T A122910 5367485952,42954566656,343577810944,2748857364480,21989919383552,
%U A122910 175923113148416,1407369872769024,11259019111628800,90071912374730752
%N A122910 Expansion of (1-2x-3x^2)/((1-2x)(1+4x)(1-8x)).
%C A122910 Let M be the matrix M(n,k)=J(k+1)*sum{j=0..n, (-1)^(n-j)C(n,j)C(j+1,k+1)}. a(n) gives the row sums of M^3.
%H A122910 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (6,24,-64).
%F A122910 G.f.: (1-2x-3x^2)/(1-6x-24x^2+64x^3); a(n)=5*8^n/8+7*(-4)^n/24+2^n/12; a(n)=J(n)*A083424(n-1)+J(n+1)*A083424(n) where J(n) are the Jacobsthal numbers A001045(n).
%F A122910 a(0)=1, a(1)=4, a(2)=45, a(n)=6*a(n-1)+24*a(n-2)-64*a(n-3). - _Harvey P. Dale_, Jun 21 2011
%t A122910 CoefficientList[Series[(1-2x-3x^2)/((1-2x)(1+4x)(1-8x)),{x,0,30}],x] (* or *) LinearRecurrence[{6, 24, -64}, {1, 4, 45}, 30] (* _Harvey P. Dale_, Jun 21 2011 *)
%K A122910 easy,nonn
%O A122910 0,2
%A A122910 _Paul Barry_, Sep 18 2006