1,1

Conjecture: a(n) > 0 for all n.

Charles R Greathouse IV, Table of n, a(n) for n = 1..100000

Charles R Greathouse IV, GP script for efficiently computing the sequence

a(1) = 2 because phi(5) = 2^2. a(11) = 3 because phi(13315) = 22^3 but phi(k) is not equal to 22^2 for any k.

(PARI) a(n)=my(k=2); while(!istotient((2*n)^k), k++); k

Cf. A000010, A002202, A065528, A227534, A227535.

Sequence in context: A103379 A032550 A036450 * A235124 A235125 A238418

Adjacent sequences: A227530 A227531 A227532 * A227534 A227535 A227536

nonn

Charles R Greathouse IV, Jul 14 2013

approved