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 A356021 #4 Jul 25 2022 10:43:19
%S A356021 1,2,3,4,8,9,10,12,16,18,20,21,24,27,32,40,45,48,50,54,63,64,72,75,80,
%T A356021 81,84,90,96,100,108,110,126,128,135,144,147,160,162,168,189,192,200,
%U A356021 220,243,250,256,270,273,288,300,320,324,336,350,360,375,378,384
%N A356021 Positive numbers k such that, for any consecutive prime numbers p, q <= A006530(n), the p-adic and q-adic valuations of n are different.
%C A356021 Equivalently, these are fixed points of A356014.
%C A356021 This sequence is infinite as it contains A066205 and A066206.
%C A356021 If m is a term, then m^k is a term (for any k >= 0).
%o A356021 (PARI) is(n) = { my (v=-1); forprime (p=2, oo, if (n==1, return (1), v==v=valuation(n,p), return (0), n\=p^v)) }
%Y A356021 Cf. A006530, A066205, A066206, A356014.
%K A356021 nonn
%O A356021 1,2
%A A356021 _Rémy Sigrist_, Jul 23 2022