A247963 Numbers n such that 57^n + 2 is prime.

0, 1, 2, 4, 5, 54, 81, 310, 360, 1117, 1410, 3320, 66162

Offset

1,3

Comments

Numbers of the form 4*h+3 are not in the sequence, since in this case 57^n+2 is divisible by 5.

Numbers ending with 6 are not in the sequence, since in this case 57^n+2 is divisible by 11.

If n == 10 mod 16, 57^n+2 is divisible by 17. - Derek Orr, Oct 04 2014

a(14) > 2*10^5. - Robert Price, Jun 11 2015

Links

Table of n, a(n) for n=1..13.

Henri & Renaud Lifchitz, PRP Top Records: Search for 57^n+2.

Mathematica

Select[Range[0, 2000], PrimeQ[57^# + 2] &]

Prog

(Magma) [n: n in [0..300]| IsPrime( 57^n + 2 )];
(PARI) for(n=1, 10^3, if(ispseudoprime(57^n+2), print1(n, ", "))) \\ Derek Orr, Oct 04 2014

Crossrefs

Cf. similar sequences listed in A247957.

Sequence in context: A167454 A056683 A065574 * A105288 A242915 A066684

Adjacent sequences: A247960 A247961 A247962 * A247964 A247965 A247966

Keyword

nonn,more

Author

Vincenzo Librandi, Oct 03 2014

Extensions

Edited by Bruno Berselli, Oct 04 2014

a(13) from Robert Price, Jun 11 2015

Status

approved