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 A105580 #20 Mar 08 2024 12:15:27
%S A105580 -5,6,0,-11,17,-6,-22,45,-29,-38,112,-103,-47,262,-318,9,571,-898,336,
%T A105580 1133,-2367,1570,1930,-5867,5507,2290,-13664,16881,-927,-29618,47426,
%U A105580 -18735,-58309,124470,-84896,-97883,307249,-294262,-110870,712381,-895773,72522,1535632,-2503927,1040817,2998742
%N A105580 a(n+3) = a(n) - a(n+1) - a(n+2); a(0) = -5, a(1) = 6, a(2) = 0.
%C A105580 Floretion Algebra Multiplication Program, FAMP Code: 2tesforseq[.5'j + .5'k + .5j' + .5k' + .5'ii' + .5e], 1vesforseq = A000004, ForType: 1A.
%H A105580 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (-1,-1,1).
%F A105580 G.f. (5-x-x^2)/(x^3-x^2-x-1)
%F A105580 a(n) = A078046(n-1) - A073145(n+3).
%F A105580 a(n) = -5*A057597(n+2) + A057597(n+1)+A057597(n). - _R. J. Mathar_, Oct 25 2022
%e A105580 This sequence was generated using the same floretion which generated the sequences A105577, A105578, A105579, etc.. However, in this case a force transform was applied. [Specifically, (a(n)) may be seen as the result of a tesfor-transform of the zero-sequence A000004 with respect to the floretion given in the program code.]
%t A105580 Transpose[NestList[Join[Rest[#],ListCorrelate[ {1,-1,-1}, #]]&,{-5,6,0},50]][[1]] (* _Harvey P. Dale_, Mar 14 2011 *)
%t A105580 CoefficientList[Series[(5-x-x^2)/(x^3-x^2-x-1),{x,0,50}],x] (* _Harvey P. Dale_, Mar 14 2011 *)
%Y A105580 Cf. A002249, A014551, A078020, A105577, A105578, A105581.
%K A105580 sign,easy
%O A105580 0,1
%A A105580 _Creighton Dement_, Apr 14 2005