A247959 Numbers n such that 39^n + 2 is prime.

0, 1, 2, 5, 6, 13, 22, 93, 99, 132, 217, 539, 1185, 28840, 70666, 105456, 116749

Offset: 1

Author

Vincenzo Librandi, Sep 28 2014

Keywords

• nonn
• more

Comments

Numbers ending with 4 are not in the sequence, since 39^n+2 is divisible by 11 for such numbers. - Bruno Berselli and M. F. Hasler, Oct 02 2014

a(18) > 2*10^5. - Robert Price, Apr 14 2015

Links

• Henri & Renaud Lifchitz, PRP Top Records, Search for 39^n + 2.

Crossrefs

Cf. similar sequences listed in A247957.

Programs

Magma

[n: n in [0..500]| IsPrime(39^n+2)];

Mathematica

Select[Range[0, 2000], PrimeQ[39^# + 2] &]

PARI

for(n=0,9e9,ispseudoprime(39^n+2)&&print1(n",")) \\ M. F. Hasler, Oct 02 2014

Extensions

a(14)-a(17) from Robert Price, Apr 14 2015