A229542 Numbers n such that (19^n - 2^n)/17 is prime.

11, 19, 79, 631, 1787, 2011, 2381, 20219, 49523

Offset: 1

Author

Robert Price, Sep 25 2013

Keywords

• nonn
• hard
• more

Comments

All terms are primes.

a(10) > 2*10^5.

Crossrefs

Cf. A128032, A225955, A225807, A006035.

Programs

Mathematica

Select[ Prime[ Range[1, 100000] ], PrimeQ[ (19^# - 2^#)/17 ]& ]

PARI

is(n)=ispseudoprime((19^n-2^n)/17) \\ Charles R Greathouse IV, Jun 13 2017