A231329 Numbers n such that (19^n + 4^n)/23 is prime.

7, 11, 211, 14461

Offset

1,1

Comments

Conjecture: All terms are prime.

a(5) > 10^5.

Links

Table of n, a(n) for n=1..4.

Mathematica

Select[ Prime[ Range[1, 100000] ], PrimeQ[ (19^# + 4^#)/23 ]& ]

Prog

(PARI) is(n)=ispseudoprime((19^n+4^n)/23) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Cf. A227049, A228558, A128075, A229612.

Sequence in context: A106716 A292791 A106818 * A322950 A201120 A164328

Adjacent sequences: A231326 A231327 A231328 * A231330 A231331 A231332

Keyword

hard,nonn,more

Author

Robert Price, Nov 07 2013

Status

approved