A213176 Numbers n such that (13^n + 4^n)/17 is prime.

7, 11, 31, 59, 73, 137, 563, 34819, 48751, 73849

Offset: 1

Author

Robert Price, May 03 2013

Keywords

• hard
• nonn
• more

Comments

All terms are prime.

a(11) > 10^5.

Crossrefs

Cf. A057179, A128071, A128342, A224501, A225097.

Programs

Mathematica

Select[ Prime[ Range[1, 100000] ], PrimeQ[ (13^# + 4^#)/17 ]& ]

PARI

is(n)=ispseudoprime((13^n+4^n)/17) \\ Charles R Greathouse IV, Jun 06 2017