A138050 Numbers k such that 23^k + 2 is prime.

0, 11, 39, 323, 12415, 14655, 27679

Offset: 1

Author

Alexander Adamchuk, Mar 02 2008

Keywords

• nonn
• more

Comments

No further terms < 100000. - Ray Chandler, Aug 03 2011

Links

• Henri & Renaud Lifchitz, PRP Records.

Crossrefs

Cf. A051783 (k such that 3^k + 2 is prime).

Cf. A087885 (k such that 5^k + 2 is prime).

Cf. A090649, A109076, A113480, A138048, A138049, A138051, A087886, A113481.

Programs

Mathematica

Do[ f = 23^n + 2; If[ PrimeQ[ f ], Print[ {n, f} ] ], {n, 1, 323} ]

PARI

is(n)=ispseudoprime(23^n+2) \\ Charles R Greathouse IV, Feb 17 2017

Extensions

a(5)-a(7) from Ray Chandler, Aug 01 2011