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 A165326 #20 Jan 03 2024 08:50:22
%S A165326 1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,
%T A165326 -1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,
%U A165326 1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1
%N A165326 a(0)=a(1)=1, a(n) = -a(n-1) for n > 1.
%C A165326 Inverse binomial transform of A040000(n) = 1,2,2,2,2,...; binomial transform of (-1)^(n+1)*A000918(n) = 1,0,-2,6,-14,30,-62,... - _Philippe Deléham_, Sep 16 2009
%C A165326 This is also the Z-sequence of the Riordan triangle A105809. See the W. Lang link under A006232 for Riordan A- and Z-sequences. - _Wolfdieter Lang_, Oct 04 2014
%H A165326 <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (-1).
%F A165326 G.f.: (1+2*x)/(1+x).
%F A165326 E.g.f.: 2-exp(-x).
%F A165326 a(n) = -a(n-1). - _Wesley Ivan Hurt_, Apr 23 2021
%t A165326 PadRight[{1},120,{-1,1}] (* _Harvey P. Dale_, Dec 04 2012 *)
%t A165326 Join[{1},LinearRecurrence[{-1},{1},83]] (* _Ray Chandler_, Aug 12 2015 *)
%Y A165326 Cf. A033999.
%K A165326 easy,sign,mult
%O A165326 0,1
%A A165326 _Philippe Deléham_, Sep 14 2009