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 A028085 #19 Jan 09 2018 02:55:33
%S A028085 1,30,585,9450,137781,1888110,24862545,318755250,4012058061,
%T A028085 49847787990,613622150505,7503229474650,91300979746341,
%U A028085 1106997911204670,13386607046238465,161563913916523650
%N A028085 Expansion of 1/((1-3x)(1-6x)(1-9x)(1-12x)).
%H A028085 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (30,-315,1350,-1944).
%F A028085 a(n) = (3^n)*Stirling2(n+4, 4), n >= 0, with Stirling2(n, m) = A008277(n, m).
%F A028085 a(n) = Sum_{m=0..3} (A075513(4, m)*((m+1)*3)^n)/3!.
%F A028085 G.f.: 1/Product_{k=1..4} (1-3*k*x).
%F A028085 E.g.f.: (d^4/dx^4)((((exp(3*x)-1)/3)^4)/4!) = Sum_{m=0..3} (A075513(4, m)*exp(3*(m+1)*x))/3!.
%F A028085 a(n) = (12^(n+3) - 3*9^(n+3) + 3*6^(n+3) - 3^(n+3))/162. - _Yahia Kahloune_, Jun 10 2013
%F A028085 a(0)=1, a(1)=30, a(2)=585, a(3)=9450, a(n) = 30*a(n-1) - 315*a(n-2) + 1350*a(n-3) - 1944*a(n-4). - _Harvey P. Dale_, Feb 06 2015
%t A028085 CoefficientList[Series[1/((1-3x)(1-6x)(1-9x)(1-12x)),{x,0,30}],x] (* or *) LinearRecurrence[{30,-315,1350,-1944},{1,30,585,9450},30] (* _Harvey P. Dale_, Feb 06 2015 *)
%o A028085 (PARI) Vec(1/((1-3*x)*(1-6*x)*(1-9*x)*(1-12*x))+O(x^99)) \\ _Charles R Greathouse IV_, Sep 26 2012
%Y A028085 Fourth column of triangle A075498.
%Y A028085 Cf. A017933, A075515.
%K A028085 nonn,easy
%O A028085 0,2
%A A028085 _N. J. A. Sloane_