A187819 Numbers k such that (9^k + 8^k)/17 is prime.

3, 7, 13, 19, 307, 619, 2089, 7297, 75571, 76103, 98897

Offset: 1

Author

Robert Price, Dec 26 2012

Keywords

• nonn
• hard
• more

Comments

All terms are prime.

a(12) > 10^5.

Crossrefs

Cf. A181141, A128339, A057175, A125956.

Programs

Mathematica

Select[ Prime[ Range[1, 100000] ], PrimeQ[ (9^# + 8^#)/17 ]& ]

PARI

is(n)=isprime((9^n+8^n)/17) \\ Charles R Greathouse IV, Feb 17 2017