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 A122911 #14 May 10 2024 16:16:15
%S A122911 1,5,139,1645,30506,452860,7520584,118102640,1907343136,30375432640,
%T A122911 487141579904,7785180808960,124635539862016,1993587347102720,
%U A122911 31902047417780224,510395557925908480,8166626525501136896
%N A122911 Expansion of (1+x)*(1-6*x-25*x^2)/((1+2x)(1-4x)(1+8x)(1-16x)).
%C A122911 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^4.
%H A122911 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (10,120,-320,-1024).
%F A122911 G.f.: (1-5x-31x^2-25x^3)/(1-10x-120x^2+320x^3+1024x^4).
%F A122911 a(n) = 85*16^n/192+203*(-8)^n/576+55*4^n/288+(-2)^n/72.
%F A122911 a(n) = J(n)*A122910(n-1)+J(n+1)*A122910(n) where J(n) are the Jacobsthal numbers A001045(n).
%t A122911 CoefficientList[Series[(1+x)(1-6x-25x^2)/((1+2x)(1-4x)(1+8x)(1-16x)),{x,0,20}],x] (* or *) LinearRecurrence[{10,120,-320,-1024},{1,5,139,1645},20] (* _Harvey P. Dale_, Dec 04 2017 *)
%Y A122911 Cf. A001045, A122910.
%K A122911 easy,nonn
%O A122911 0,2
%A A122911 _Paul Barry_, Sep 18 2006