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 A340074 #8 Dec 30 2020 19:59:21 %S A340074 1,1,1,1,3,1,5,1,1,1,3,1,1,1,1,1,9,1,11,1,1,1,7,1,3,1,1,1,15,1,9,1,1, %T A340074 1,1,1,5,1,1,1,21,1,23,1,3,1,13,1,5,1,1,1,29,1,9,1,1,1,15,1,33,1,1,1, %U A340074 1,1,35,1,1,5,9,1,39,1,1,1,1,1,41,1,1,1,11,1,3,1,1,1,3,1,1,1,1,1,1,1,25,1,3,1,51,1,53,1,3 %N A340074 a(n) = gcd(A003961(n)-1, A339904(n)). %C A340074 Odd part of A340071(n). %H A340074 Antti Karttunen, <a href="/A340074/b340074.txt">Table of n, a(n) for n = 1..8191</a> %H A340074 Antti Karttunen, <a href="/A340074/a340074.txt">Data supplement: n, a(n) computed for n = 1..65537</a> %H A340074 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a> %F A340074 a(n) = gcd(A003961(n)-1, A339904(n)). %F A340074 a(n) = A000265(A340071(n)). %F A340074 a(n) = A339904(n) / A340075(n). %o A340074 (PARI) %o A340074 A000265(n) = (n>>valuation(n,2)); %o A340074 A003961(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); }; %o A340074 A339904(n) = A000265(eulerphi(A003961(n))); %o A340074 A340074(n) = gcd(A003961(n)-1, A339904(n)); %Y A340074 Cf. A000265, A003961, A339904, A340071, A340075. %K A340074 nonn %O A340074 1,5 %A A340074 _Antti Karttunen_, Dec 29 2020