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 A025999 #26 May 04 2025 15:06:10
%S A025999 1,26,445,6370,82901,1019746,12105885,140404290,1603014501,
%T A025999 18104952866,202945103725,2262802497410,25134485221301,
%U A025999 278430633932386,3078357517755965,33986947913921730,374856803115095301,4131429114327366306,45509760855920174605,501119725990818613250
%N A025999 Expansion of g.f. 1/((1-2*x) * (1-5*x) * (1-8*x) * (1-11*x)).
%H A025999 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (26,-231,806,-880).
%F A025999 a(n) = -4*2^n/81 +125*5^n/54 -256*8^n/27 +1331*11^n/162. - _R. J. Mathar_, Jun 20 2013
%F A025999 a(0)=1, a(1)=26, a(2)=445, a(3)=6370, a(n)=26*a(n-1)-231*a(n-2)+ 806*a(n-3)- 880*a(n-4). - _Harvey P. Dale_, May 24 2014
%F A025999 From _Seiichi Manyama_, May 04 2025: (Start)
%F A025999 a(n) = Sum_{k=0..n} 3^k * 2^(n-k) * binomial(n+3,k+3) * Stirling2(k+3,3).
%F A025999 a(n) = Sum_{k=0..n} (-3)^k * 11^(n-k) * binomial(n+3,k+3) * Stirling2(k+3,3). (End)
%F A025999 E.g.f.: exp(2*x)*(1331*exp(9*x) - 1536*exp(6*x) + 375*exp(3*x) - 8)/162. - _Stefano Spezia_, May 04 2025
%t A025999 CoefficientList[Series[1/((1-2x)(1-5x)(1-8x)(1-11x)),{x,0,20}],x] (* or *) LinearRecurrence[{26,-231,806,-880},{1,26,445,6370},20] (* _Harvey P. Dale_, May 24 2014 *)
%Y A025999 Cf. A016127, A016297.
%K A025999 nonn,easy
%O A025999 0,2
%A A025999 _N. J. A. Sloane_