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A247963
Numbers n such that 57^n + 2 is prime.
1
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
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
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