

A138048


Numbers n such that 15^n + 2 is prime.


7



0, 1, 2, 4, 5, 10, 11, 16, 20, 52, 75, 106, 112, 132, 371, 3264, 3424, 5477, 7516, 10365, 44557, 150706
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OFFSET

1,3


COMMENTS

No further terms < 100000.  Ray Chandler, Aug 05 2011
a(23) > 2*10^5.  Robert Price, Jun 23 2015


LINKS

Table of n, a(n) for n=1..22.
Henri & Renaud Lifchitz, PRP Records.


MATHEMATICA

Do[ f = 15^n + 2; If[ PrimeQ[ f ], Print[ {n, f} ] ], {n, 1, 371} ]


PROG

(PARI) is(n)=ispseudoprime(15^n+2) \\ Charles R Greathouse IV, Feb 17 2017


CROSSREFS

Cf. A051783 = Numbers n such that 3^n + 2 is prime. Cf. A087885 = Numbers n such that 5^n + 2 is prime. Cf. A090649, A109076, A113480, A138049, A138050, A138051, A087886, A113481.
Sequence in context: A236246 A004792 A167795 * A057762 A109511 A018339
Adjacent sequences: A138045 A138046 A138047 * A138049 A138050 A138051


KEYWORD

nonn,more


AUTHOR

Alexander Adamchuk, Mar 02 2008


EXTENSIONS

{3264, 3424, 5477, 7516} from Ray Chandler, Jul 30 2011
10365 found by Lelio R Paula, Dec 2006
44557 from Ray Chandler, Jul 31 2011
a(22) from Robert Price, Jun 23 2015


STATUS

approved



