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 A339901 #14 Jan 01 2021 11:43:56
%S A339901 1,1,1,1,1,3,3,3,1,5,5,5,15,3,5,15,1,3,3,3,1,9,9,9,15,15,5,15,9,45,5,
%T A339901 45,1,1,1,1,3,3,1,3,5,1,5,5,5,15,15,15,3,3,1,3,9,9,3,9,1,15,15,15,15,
%U A339901 9,45,45,1,9,9,9,9,27,27,27,45,45,5,45,135,135,45,135,9,27,27,27,3,81,81,81,135,27,45,135,405
%N A339901 a(n) = A339971(n) / gcd(A339809(2*n), A339971(n)).
%C A339901 Compare also to the scatter plot of A339898.
%H A339901 Antti Karttunen, <a href="/A339901/b339901.txt">Table of n, a(n) for n = 0..8192</a>
%H A339901 Antti Karttunen, <a href="/A339901/a339901.txt">Data supplement: n, a(n) computed for n = 0..65537</a>
%F A339901 a(n) = A339971(n) / A339899(n).
%F A339901 a(n) = A000265(A160595(A019565(2*n))).
%F A339901 a(n) = A340075(A019565(n)) = A340085(A019565(2*n)).
%o A339901 (PARI)
%o A339901 A000265(n) = (n>>valuation(n,2));
%o A339901 A019565(n) = { my(m=1, p=1); while(n>0, p = nextprime(1+p); if(n%2, m *= p); n >>= 1); (m); };
%o A339901 A339901(n) = { my(x=A019565(2*n), y=A000265(eulerphi(x))); y/gcd((x-1),y); };
%Y A339901 Cf. A000265, A053575, A019565, A160595, A339809, A339821, A339971, A339898, A339899, A340075, A340085.
%Y A339901 Cf. A339973 (positions of ones).
%K A339901 nonn,look
%O A339901 0,6
%A A339901 _Antti Karttunen_, Dec 28 2020