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 A344145 #9 May 14 2021 02:33:10
%S A344145 2,9,10,12,35,37,38,41,42,44,49,50,52,56,139,141,142,147,149,150,153,
%T A344145 154,156,163,165,166,169,170,172,177,178,180,184,197,198,201,202,204,
%U A344145 209,210,212,216,226,228,232,555,557,558,563,565,566,569,570,587,589
%N A344145 Positive numbers m such that A020330^k(m) belongs to A344022 for any k >= 0 (where f^k denotes the k-th iterate of f).
%C A344145 The binary expansion of a term, say (b_1, ..., b_m), encodes an m-periodic nonintersecting infinite walk made of unit steps, with a +90-degree turn (resp. a -90-degree turn) at positions X=k' such that b_k = 1 (resp. b_k = 0) with k = k' mod m.
%C A344145 All positive terms of A002450 belong to this sequence.
%H A344145 Rémy Sigrist, <a href="/A344145/a344145.png">Illustration of initial terms</a>
%e A344145 See illustration in Links section.
%o A344145 (PARI) is(n) = { my (b=if (n, binary(n), [0]), d=1, s=[d], z=2*d); b=concat([b,b,b,b]); for (k=1, #b, if (b[k], d*=I, d/=I); if (setsearch(s, z+=d), return (0), s=setunion(s, [z]); z+=d)); return (1) }
%Y A344145 Cf. A002450, A020330, A344022.
%K A344145 nonn,base
%O A344145 1,1
%A A344145 _Rémy Sigrist_, May 10 2021