A058590 Numbers k such that 5*3^k + 2 is prime.

0, 1, 2, 3, 5, 7, 10, 11, 13, 16, 28, 32, 56, 57, 62, 95, 111, 160, 308, 323, 855, 880, 1081, 1095, 1288, 2635, 2822, 2948, 3195, 7702, 8823, 10751, 11572, 12718, 14587, 20445, 26863, 28501, 29086, 30926, 37671, 38450, 57541, 81350, 214250

Offset

1,3

Comments

214250 also belongs to the sequence (but interval 35000-209600 was not searched). - Serge Batalov, Oct 30 2010

a(45) > 2*10^5. - Robert Price, May 16 2015

Confirmed a(45) = 214250. - Robert Price, May 21 2015

a(46) > 215000. - Robert Price, May 21 2015

Links

Table of n, a(n) for n=1..45.

Mathematica

Do[ If[ PrimeQ[ 5*3^n + 2 ], Print[ n ] ], {n, 0, 7550} ]
Select[Range[0, 2 10^3], PrimeQ[5 3^# + 2] &] (* Vincenzo Librandi, May 16 2015 *)

Prog

(Magma) [n: n in [0..1000] | IsPrime(5*3^n+2)]; // Vincenzo Librandi, May 16 2015
(PARI) is(n)=ispseudoprime(5*3^n+2) \\ Charles R Greathouse IV, Jun 13 2017
(PFGW) ABC2 5*3^$a + 2
a: from 0 to 10000 // Jinyuan Wang, Feb 01 2020

Crossrefs

Cf. A058591 (5*3^k - 2 is prime).

Sequence in context: A327203 A048461 A338174 * A187711 A064627 A324813

Adjacent sequences: A058587 A058588 A058589 * A058591 A058592 A058593

Keyword

nonn,more

Author

Robert G. Wilson v, Dec 26 2000

Extensions

More PRP terms from Serge Batalov, Oct 30 2010

a(41)-a(44) from Robert Price, May 16 2015

a(1)=0 prepended by Vincenzo Librandi, May 16 2015

a(45) discovered by Serge Batalov added by Robert Price, May 21 2015

Status

approved