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A173718 Numbers n such that (9^n - 2^n)/7 is prime. 2
2, 3, 5, 13, 29, 37, 1021, 1399, 2137, 4493, 5521 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms are prime.

a(12) > 10^5.

LINKS

Table of n, a(n) for n=1..11.

MATHEMATICA

Select[ Prime[ Range[1, 100000] ], PrimeQ[ (9^# - 2^#)/7 ]& ]

PROG

(PARI) is(n)=ispseudoprime((9^n-2^n)/7) \\ Charles R Greathouse IV, Jun 06 2017

CROSSREFS

Cf. A004063, A028491, A057468, A059801, A121877, A128024, A128025, A128026, A128027, A128028, A128029, A128030, A128031, A128032.

Sequence in context: A289758 A089477 A099962 * A281316 A177502 A072536

Adjacent sequences:  A173715 A173716 A173717 * A173719 A173720 A173721

KEYWORD

hard,more,nonn

AUTHOR

Robert Price, Dec 22 2012

STATUS

approved

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Last modified November 21 05:01 EST 2017. Contains 294988 sequences.