A247957 Numbers n such that 33^n + 2 is prime.

0, 2, 26, 60, 218, 248, 399, 1175, 1244, 2670, 9300, 45216, 144412

Offset

1,2

Comments

Some terms correspond to probable primes. Lifchitz link shows that Ray Chandler discovered 9300, and Lelio R Paula found that 45216 is in the sequence. - Jens Kruse Andersen, Sep 29 2014

Terms in the similar sequence, 53^n+2, begin with 0, 7, 14483 with the next term > 2*10^5. - Robert Price, Mar 28 2015

Confirmed that 45216 is a(12). - Robert Price, Apr 14 2015

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

Links

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

Henri & Renaud Lifchitz, PRP Records, search for 33^n+2

Maple

A247957:=n->`if`(isprime(33^n+2), n, NULL): seq(A247957(n), n=0..1000); # Wesley Ivan Hurt, Sep 28 2014

Mathematica

Select[Range[0, 1000], PrimeQ[33^# + 2] &]

Prog

(Magma) [n: n in [0..350]| IsPrime( 33^n + 2 )]
(PARI) is(n)=ispseudoprime(33^n+2) \\ Charles R Greathouse IV, Feb 17 2017

Crossrefs

Cf. numbers n such that k^n+2 is prime: A051783 (k=3), A087885 (k=5), A090649 (k=9), A109076 (k=11), A138048 (k=15), A113480 (k=17), A138049 (k=21), A138050 (k=23), A138051 (k=27), A087886 (k=29), this sequence (k=33), A247958 (k=35), A247959 (k=39), A247960 (k=41), A247961 (k=45); (0, 113) for k=47; A247962 (k=51); A247963 (k=57), A113481 (k=59).

Sequence in context: A199206 A132861 A210848 * A152997 A345693 A229573

Adjacent sequences: A247954 A247955 A247956 * A247958 A247959 A247960

Keyword

nonn,more

Author

Vincenzo Librandi, Sep 28 2014

Extensions

a(8)-a(11) from Jens Kruse Andersen, Sep 29 2014

a(12)-a(13) from Robert Price, Apr 14 2015

Status

approved