A216890 Numbers n such that 14*3^n + 1 is prime.

1, 2, 3, 18, 22, 26, 27, 33, 39, 57, 62, 94, 145, 246, 390, 398, 402, 571, 690, 906, 1062, 1254, 1367, 1627, 1954, 2409, 3107, 14754, 15378, 24219, 46138, 98883, 161178

Offset: 1

Author

Vincenzo Librandi, Sep 26 2012

Keywords

• nonn

Comments

The next terms are > 6000.

a(34) > 2*10^5. - Robert Price, Mar 16 2014

All terms are verified primes (i.e., not probable primes). - Robert Price, Mar 16 2014

Crossrefs

Cf. A003306, A005537-A005539, A056805.

Programs

Magma

[n: n in [0..4000] | IsPrime(14*3^n+1)];

Mathematica

Select[Range[4000], PrimeQ[14 3^# + 1] &]

PARI

is(n)=ispseudoprime(14*3^n+1) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(28)-a(33) from Robert Price, Mar 16 2014