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 A108404 #13 Sep 22 2017 10:01:30
%S A108404 1,4,21,124,761,4724,29421,183404,1143601,7131364,44471301,277325404,
%T A108404 1729418921,10784771924,67254567261,419404046924,2615432135521,
%U A108404 16310012568004,101710347053301,634272638178364,3955367287840601
%N A108404 Expansion of (1-4x)/(1-8x+11x^2).
%C A108404 Binomial transform of A098648. Second binomial transform of A001077. Third binomial transform of A084057. 4th binomial transform of (1, 0, 5, 0, 25, 0, 125, 0, 625, 0, 3125, ...).
%H A108404 Seiichi Manyama, <a href="/A108404/b108404.txt">Table of n, a(n) for n = 0..1258</a>
%H A108404 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (8,-11).
%F A108404 E.g.f.: exp(4x)cosh(sqrt(5)x).
%F A108404 a(n) = 8a(n-1) - 11a(n-2), a(0) = 1, a(1) = 4.
%F A108404 a(n) = ((4+sqrt(5))^n + (4-sqrt(5))^n)/2.
%F A108404 a(n+1)/a(n) converges to 4 + sqrt(5) = 6.2360679774997896964... = 4+A002163.
%F A108404 a(n) = A091870(n+1)-4*A091870(n). - _R. J. Mathar_, Nov 10 2013
%t A108404 CoefficientList[Series[(1-4x)/(1-8x+11x^2),{x,0,30}],x] (* or *) LinearRecurrence[{8,-11},{1,4},30] (* _Harvey P. Dale_, Jan 03 2012 *)
%Y A108404 Cf. A001077, A084057, A098648.
%K A108404 easy,nonn
%O A108404 0,2
%A A108404 _Philippe Deléham_, Jul 04 2005