1,2

There is no further term up to 5*10^7.

Table of n, a(n) for n=1..5.

652245 is in the sequence because prime(652245)=d(652245)*phi(652245)+1.

Do[If[Prime[n] == DivisorSigma[0, n]*EulerPhi[n] + 1, Print[n]], {n, 50000000}]

Cf. A104905, A107657.

Sequence in context: A228311 A258107 A307256 * A024595 A144804 A118308

Adjacent sequences: A107653 A107654 A107655 * A107657 A107658 A107659

more,nonn

Farideh Firoozbakht, Jun 06 2005

approved