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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified December 13 17:30 EST 2017. Contains 295959 sequences.