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 A077850 #24 Jul 31 2015 12:07:56
%S A077850 1,3,8,19,44,100,226,509,1145,2574,5785,13000,29212,65640,147493,
%T A077850 331415,744684,1673291,3759852,8448312,18983186,42654833,95844541,
%U A077850 215360730,483911169,1087338528,2443227496,5489882352,12335653673,27717962203,62281695728,139945699987
%N A077850 Expansion of (1-x)^(-1)/(1 - 2*x - x^2 + x^3).
%C A077850 a(n) = A052534(n+1) - 1.
%H A077850 Harvey P. Dale, <a href="/A077850/b077850.txt">Table of n, a(n) for n = 0..1000</a>
%H A077850 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (3, -1, -2, 1).
%F A077850 a(n) = sum(k=0..n+2, A006054(k)). - _Philippe Deléham_, Sep 07 2006
%F A077850 a(n) = 3*a(n-1) - a(n-2) - 2*a(n-3) + a(n-4), n>3. Also a(n)=Sum_{k=0..n} A188106(n,k), n=0,1,2,..., giving partial sums of first convolution of A006054 with itself. - _L. Edson Jeffery_, Apr 22 2011
%t A077850 CoefficientList[Series[(1-x)^(-1)/(1-2x-x^2+x^3),{x,0,40}],x] (* or *) LinearRecurrence[{3,-1,-2,1},{1,3,8,19},40] (* _Harvey P. Dale_, Jan 22 2013 *)
%o A077850 (PARI) Vec(1/(1-x)/(1-2*x-x^2+x^3)+O(x^99)) \\ _Charles R Greathouse IV_, Sep 26 2012
%Y A077850 Cf. A188106. See also A189247. - _L. Edson Jeffery_, Apr 22 2011
%K A077850 nonn,easy
%O A077850 0,2
%A A077850 _N. J. A. Sloane_, Nov 17 2002