A070800 Smallest prime greater than phi(n): a(n) = nextprime(phi(n)).

2, 3, 3, 5, 3, 7, 5, 7, 5, 11, 5, 13, 7, 11, 11, 17, 7, 19, 11, 13, 11, 23, 11, 23, 13, 19, 13, 29, 11, 31, 17, 23, 17, 29, 13, 37, 19, 29, 17, 41, 13, 43, 23, 29, 23, 47, 17, 43, 23, 37, 29, 53, 19, 41, 29, 37, 29, 59, 17, 61, 31, 37, 37, 53, 23, 67, 37, 47, 29, 71, 29, 73, 37

Offset: 2

Author

Labos Elemer, May 08 2002

Keywords

• easy
• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 2..16384

Crossrefs

Cf. A000010, A070801, A151800, A078773.

Programs

Mathematica

Table[Prime[1+PrimePi[EulerPhi[w]]], {w, 2, 128}] (* or *)
NextPrime[EulerPhi[#]] & /@ Range[2,80] (* Harvey P. Dale, Jan 30 2011 *)

PARI

a(n)=nextprime(eulerphi(n)+1) \\ Charles R Greathouse IV, Oct 31 2011

Formula

a(n) = prime(1 + primepi(phi(n))) = A151800(A000010(n)).