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 A152833 #10 Jan 09 2021 13:53:07
%S A152833 -3,4,-2,5,-1,6,0,7,1,8,2,9,3,10,4,11,5,12,6,13,7,14,8,15,9,16,10,17,
%T A152833 11,18,12,19,13,20,14,21,15,22,16,23,17,24,18,25,19,26,20,27,21,28,22,
%U A152833 29,23,30,24,31,25,32,26,33,27,34,28,35,29,36,30,37,31,38,32,39,33,40,34
%N A152833 a(0) = -3; a(n) = n-a(n-1).
%F A152833 a(n) = (2n+1-13*(-1)^n)/4. G.f.: -(3-7x+3x^2)/((1+x)(1-x)^2). - _R. J. Mathar_, Jan 08 2009
%t A152833 lst={};a=3;Do[a=n-a;AppendTo[lst,a],{n,0,6!}];lst
%t A152833 RecurrenceTable[{a[0]==-3,a[n]==n-a[n-1]},a,{n,80}] (* _Harvey P. Dale_, May 16 2016 *)
%Y A152833 Cf. A084964, A152832.
%K A152833 sign
%O A152833 0,1
%A A152833 _Vladimir Joseph Stephan Orlovsky_, Dec 14 2008
%E A152833 Indices added to definition, offset corrected by _R. J. Mathar_, Jan 08 2009