A213216 Numbers n such that (12^n + 11^n)/23 is prime.

47, 401, 509, 8609

Offset: 1

Author

Robert Price, Mar 02 2013

Keywords

• hard
• nonn
• more

Comments

All terms are prime.

a(5) > 10^5.

Crossrefs

Cf. A057178, A128341, A181141, A187819, A217095.

Programs

Mathematica

Select[ Prime[ Range[1, 100000] ], PrimeQ[ (12^# + 11^#)/23 ]& ]

PARI

is(n)=ispseudoprime((12^n+11^n)/23) \\ Charles R Greathouse IV, Feb 20 2017

Extensions

Removed incorrect first term of "2".