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 A143098 #14 Jun 02 2025 04:57:48
%S A143098 1,2,-1,2,2,-1,2,2,-1,2,2,-1,2,2,-1,2,2,-1,2,2,-1,2,2,-1,2,2,-1,2,2,
%T A143098 -1,2,2,-1,2,2,-1,2,2,-1,2,2,-1,2,2,-1,2,2,-1,2,2,-1,2,2,-1,2,2,-1,2,
%U A143098 2,-1,2,2,-1,2,2,-1,2,2,-1,2,2,-1,2,2,-1,2,2,-1,2
%N A143098 First differences of A143097.
%C A143098 Binomial transform gives A143100.
%C A143098 1 followed by {2, -1, 2} repeated. - _Amiram Eldar_, Jun 02 2025
%F A143098 G.f.: x(1+2x-x^2+x^3)/((1-x)(1+x+x^2)). - _R. J. Mathar_, Sep 06 2008
%t A143098 Join[{1}, Flatten[Table[{2, -1, 2}, {33}]]] (* _Amiram Eldar_, Jun 02 2025 *)
%Y A143098 Cf. A143097, A143100.
%K A143098 sign,easy
%O A143098 1,2
%A A143098 _Gary W. Adamson_, Jul 24 2008