1,5

A companion sequence of A094269.

Table of n, a(n) for n=1..82.

phi(A003401(n)) = A094269(n) = 2^a(n).

(PARI) for(n=1, 1e4, my(i=eulerphi(n)); if(omega(2*i)==1, print1(logint(i, 2), ", ")))

A000010, A003401, A094269.

Sequence in context: A029258 A280128 A070096 * A024154 A117875 A084840

Adjacent sequences: A319818 A319819 A319820 * A319822 A319823 A319824

nonn

Jianing Song, Sep 28 2018

approved