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 A319821 #17 Sep 25 2024 02:36:31 %S A319821 0,0,1,1,2,1,2,2,2,3,3,4,3,3,3,4,4,4,4,5,4,5,5,5,6,5,5,5,6,6,6,6,6,6, %T A319821 6,7,7,8,7,7,7,7,7,7,7,8,8,8,8,8,8,9,8,8,8,9,9,9,9,10,9,9,9,9,9,9,10, %U A319821 10,10,10,10,10,10,10,10,10,11,10,11,11,11,12 %N A319821 a(n) = log_2(A094269(n)). %C A319821 A companion sequence of A094269. %H A319821 Amiram Eldar, <a href="/A319821/b319821.txt">Table of n, a(n) for n = 1..10000</a> %F A319821 2^a(n) = A094269(n) = phi(A003401(n)). %o A319821 (PARI) for(n=1, 1e4, my(i=eulerphi(n)); if(omega(2*i)==1, print1(logint(i,2), ", "))) %Y A319821 Cf. A000010, A003401, A094269. %K A319821 nonn %O A319821 1,5 %A A319821 _Jianing Song_, Sep 28 2018