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 A077833 #12 Sep 07 2017 12:48:18
%S A077833 1,2,7,22,69,218,687,2166,6829,21530,67879,214006,674709,2127194,
%T A077833 6706527,21144054,66662077,210169370,662613079,2089058422,6586294821,
%U A077833 20764991066,65466983439,206401529718,650733991885,2051606539802,6468218114695,20392723832566
%N A077833 Expansion of 1/(1-2*x-3*x^2-2*x^3).
%H A077833 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (2,3,2).
%t A077833 CoefficientList[Series[1/(1-2x-3x^2-2x^3),{x,0,30}],x] (* or *) LinearRecurrence[{2,3,2},{1,2,7},30] (* _Harvey P. Dale_, Sep 07 2017 *)
%o A077833 (PARI) Vec(1/(1-2*x-3*x^2-2*x^3)+O(x^99)) \\ _Charles R Greathouse IV_, Sep 27 2012
%Y A077833 Partial sums of S(n, x), x=1..19 see A077832 and A-number references.
%Y A077833 First differences of A077826.
%K A077833 nonn,easy
%O A077833 0,2
%A A077833 _N. J. A. Sloane_, Nov 17 2002