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 A364291 #6 Jul 25 2023 12:31:20
%S A364291 1,2,3,4,6,8,9,12,15,16,18,24,25,27,30,32,35,36,45,48,49,50,54,60,63,
%T A364291 64,70,72,75,77,81,90,96,98,100,105,108,120,121,125,126,128,135,140,
%U A364291 143,144,147,150,154,162,165,169,175,180,189,192,196,200,210,216,225,231,240,242,243,245,250,252,256,270,273
%N A364291 Numbers k such that A243071(k) <= k.
%C A364291 If k is present, then 2*k is also present, and vice versa.
%o A364291 (PARI)
%o A364291 A064989(n) = { my(f=factor(n>>valuation(n,2))); for(i=1, #f~, f[i,1] = precprime(f[i,1]-1)); factorback(f); };
%o A364291 A243071(n) = if(n<=2, n-1, if(!(n%2), 2*A243071(n/2), 1+(2*A243071(A064989(n)))));
%o A364291 isA364291(n) = (A243071(n)<=n);
%Y A364291 Positions of nonnegative terms in A364288.
%Y A364291 Cf. A007283, A364290 (subsequences).
%Y A364291 Cf. A243071.
%Y A364291 Cf. also A364287.
%K A364291 nonn
%O A364291 1,2
%A A364291 _Antti Karttunen_, Jul 25 2023