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 A078031 #24 Sep 08 2022 08:45:08
%S A078031 1,-1,-1,2,0,-3,2,3,-5,-1,8,-4,-9,12,5,-21,7,26,-28,-19,54,-9,-73,63,
%T A078031 64,-136,-1,200,-135,-201,335,66,-536,269,602,-805,-333,1407,-472,
%U A078031 -1740,1879,1268,-3619,611,4887,-4230,-4276,9117,46,-13393,9071,13439,-22464,-4368,35903,-18096
%N A078031 Expansion of (1-x)/(1 + x^2 - x^3).
%C A078031 The Ca2 sums, see A180662, of triangle A108299 equal the terms of this sequence. - _Johannes W. Meijer_, Aug 14 2011
%H A078031 G. C. Greubel, <a href="/A078031/b078031.txt">Table of n, a(n) for n = 0..1000</a>
%H A078031 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (0,-1,1).
%F A078031 G.f.: (1-x)/(1 + x^2 - x^3).
%F A078031 a(n) = -a(n-2) + a(n-3); a(0)=1, a(1)=-1, a(2)=-1. - _Harvey P. Dale_, Apr 08 2012
%p A078031 A078031 := proc(n) option remember: coeftayl((1-x)/(1+x^2-x^3),x=0,n) end: seq(A078031(n), n=0..60); # _Johannes W. Meijer_, Aug 14 2011
%t A078031 CoefficientList[Series[(1-x)/(1+x^2-x^3),{x,0,60}],x] (* or *) LinearRecurrence[{0,-1,1},{1,-1,-1},60] (* _Harvey P. Dale_, Apr 08 2012 *)
%o A078031 (PARI) Vec((1-x)/(1+x^2-x^3)+O(x^60)) \\ _Charles R Greathouse IV_, Sep 26 2012
%o A078031 (Magma) R<x>:=PowerSeriesRing(Integers(), 60); Coefficients(R!( (1-x)/(1+x^2-x^3) )); // _G. C. Greubel_, Aug 05 2019
%o A078031 (Sage) ((1-x)/(1+x^2-x^3)).series(x, 60).coefficients(x, sparse=False) # _G. C. Greubel_, Aug 05 2019
%o A078031 (GAP) a:=[1,-1,-1];; for n in [4..60] do a[n]:=-a[n-2]+a[n-3]; od; a; # _G. C. Greubel_, Aug 05 2019
%Y A078031 Cf. A077961, A108299, A180662. - _Johannes W. Meijer_, Aug 14 2011
%K A078031 sign,easy
%O A078031 0,4
%A A078031 _N. J. A. Sloane_, Nov 17 2002