A109887 Numbers n such that 3^n + phi(n) is prime.

3, 4, 10, 20, 44, 60, 583, 677, 947, 1182, 12048, 16018, 74316

Offset

1,1

Comments

All terms correspond to certified primes (Primo 2.2.0 beta). No more terms through 10000.

a(14) > 10^5. [From Donovan Johnson, Feb 06 2010]

Links

Table of n, a(n) for n=1..13.

Mathematica

Do[If[PrimeQ[3^n + EulerPhi[n]], Print[n]], {n, 1, 10000}]

Crossrefs

Sequence in context: A326832 A357812 A321197 * A200981 A266729 A103038

Adjacent sequences: A109884 A109885 A109886 * A109888 A109889 A109890

Keyword

hard,nonn

Author

Ryan Propper, Aug 31 2005

Extensions

a(11)-a(13) from Donovan Johnson, Feb 06 2010

Status

approved