A247962 Numbers n such that 51^n + 2 is prime.

0, 1, 5, 6, 15, 24, 25, 66, 72, 309, 330, 594, 1000, 1142, 1882, 2482, 2725, 30106, 65176, 85334

Offset: 1

Author

Vincenzo Librandi, Oct 02 2014

Keywords

• nonn
• more

Comments

Numbers ending with 8 are not in the sequence. - Bruno Berselli, Oct 02 2014

a(21) > 2*10^5. - Robert Price, Jul 07 2015

Links

• Henri & Renaud Lifchitz, PRP Top Records, Search for 51^n+2.

Crossrefs

Cf. similar sequences listed in A247957.

Programs

Magma

[n: n in [0..300]| IsPrime( 51^n + 2 )];

Maple

A247962:=n->`if`(isprime(51^n+2),n,NULL): seq(A247962(n),n=0..500); # Wesley Ivan Hurt, Oct 02 2014

Mathematica

Select[Range[0, 2000], PrimeQ[51^# + 2] &]

PARI

is(n)=ispseudoprime(51^n+2) \\ Charles R Greathouse IV, Jun 06 2017

Extensions

a(16)-a(20) from Robert Price, Jul 07 2015