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 A077883 #21 Aug 14 2024 08:30:25
%S A077883 1,1,2,1,2,0,2,-1,3,-2,5,-4,8,-8,13,-15,22,-27,38,-48,66,-85,115,-150,
%T A077883 201,-264,352,-464,617,-815,1082,-1431,1898,-2512,3330,-4409,5843,
%U A077883 -7738,10253,-13580,17992,-23832,31573,-41823,55406,-73395,97230,-128800,170626,-226029,299427,-396654
%N A077883 Expansion of (1-x)^(-1)/(1-x^2+x^3).
%H A077883 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (1,1,-2,1).
%F A077883 G.f.: (1-x)^(-1)/(1-x^2+x^3).
%F A077883 a(n) = a(n-1) + a(n-2) - 2*a(n-3) + a(n-4) with a(0)=1, a(1)=1, a(2)=2, a(3)=1. - _Harvey P. Dale_, Mar 26 2012
%F A077883 a(n) = (-1)^n * Sum_{k=0..floor(n/2)} binomial(k-1,n-2*k). - _Seiichi Manyama_, Aug 14 2024
%t A077883 CoefficientList[Series[(1-x)^(-1)/(1-x^2+x^3),{x,0,60}],x] (* or *) LinearRecurrence[{1,1,-2,1},{1,1,2,1},60] (* _Harvey P. Dale_, Mar 26 2012 *)
%o A077883 (PARI) Vec((1-x)^(-1)/(1-x^2+x^3)+O(x^99)) \\ _Charles R Greathouse IV_, Sep 27 2012
%o A077883 (PARI) a(n) = (-1)^n*sum(k=0, n\2, binomial(k-1, n-2*k)); \\ _Seiichi Manyama_, Aug 14 2024
%Y A077883 Cf. A375364, A375372.
%K A077883 sign,easy
%O A077883 0,3
%A A077883 _N. J. A. Sloane_, Nov 17 2002