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 A325599 #8 Dec 15 2024 16:28:43
%S A325599 1,1,1,2,1,2,1,2,1,1,1,2,1,1,2,1,1,1,2,1,1,2,1,1,1,2,1,1,2,1,2,1,2,1,
%T A325599 1,1,2,1,1,2,1,2,1,1,1,2,1,1,2,1,2,1,2,1,1,1,2,1,1,2,1,2,1,1,1,2,1,1,
%U A325599 2,1,2,1,2,1,1,1,2,1,1,2,1,2,1,1,1,2
%N A325599 Difference sequence of A325597.
%C A325599 All the terms of A325599 are in {1,2}, so that A325600 and A325601 are a complementary pair.
%H A325599 Clark Kimberling, <a href="/A325599/b325599.txt">Table of n, a(n) for n = 1..10000</a>
%t A325599 mex[list_, start_] := (NestWhile[# + 1 &, start, MemberQ[list, #] &]); a = {1}; Do[AppendTo[a, mex[Rest[2 a] + Most[a], Last[a] + 1]], {60}]; a (* A325597 *)
%t A325599 c = Complement[Range[Last[a]], a] (* A325598 *)
%t A325599 da = Differences[a] (* A325599 *)
%t A325599 Flatten[Position[da, 1]] (* A325600 *)
%t A325599 Flatten[Position[da, 2]] (* A325601 *)
%t A325599 (* _Peter J. C. Moses_, May 07 2019 *)
%Y A325599 Cf. A325597.
%K A325599 nonn,easy
%O A325599 1,4
%A A325599 _Clark Kimberling_, May 11 2019