A319821 - OEIS

A319821

a(n) = log_2(A094269(n)).

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, 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, 10, 10, 10, 10, 10, 10, 10, 10, 10, 11, 10, 11, 11, 11, 12

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,5

COMMENTS

A companion sequence of A094269.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

FORMULA

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

PROG

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

CROSSREFS