login
A163665
Numbers n such that n=prime(phi(sigma(pi(n)))).
1
2, 3, 19, 37, 719, 1511, 5443, 69709, 386093, 1907819, 10777931, 17819101, 18653749, 56125547, 60163267, 98911811, 272887613, 567611663, 989060309, 2444540149
OFFSET
1,1
COMMENTS
It is obvious that all terms are primes. There is no further term up to 5*10^9.
MATHEMATICA
Do[If[n=Prime[m]; m==EulerPhi[DivisorSigma[1, PrimePi[n]]], Print[n]], {m, 235000000}]
CROSSREFS
KEYWORD
more,nonn
AUTHOR
Farideh Firoozbakht, Aug 04 2009
STATUS
approved