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A128455 Numbers n such that 9^n - 2 is a prime. 13
1, 2, 3, 11, 45, 51, 260, 324, 390, 393, 1112, 3092, 4445, 10373, 15861, 18528, 97715, 112961 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(19) > 2*10^5. - Robert Price, Aug 18 2014

LINKS

Table of n, a(n) for n=1..18.

MATHEMATICA

Do[ f = 9^n - 2; If[ PrimeQ[ f ], Print[ {n, f} ] ], {n, 1, 1000} ]

CROSSREFS

Cf. A084714 = smallest prime of the form (2n-1)^k - 2, or 0 if no such number exists. Cf. A128472 = smallest prime of the form (2n-1)^k - 2 for k>(2n-1), or 0 if no such number exists. Cf. A014224, A109080, A090669, A128457, A128458, A128459, A128460, A128461.

Sequence in context: A051093 A107327 A162101 * A260159 A287060 A041345

Adjacent sequences:  A128452 A128453 A128454 * A128456 A128457 A128458

KEYWORD

hard,more,nonn

AUTHOR

Alexander Adamchuk, Mar 14 2007

EXTENSIONS

1112 from Stefan Steinerberger, May 05 2007

More terms from Ryan Propper, Jan 12 2008

a(15)-a(18) from Robert Price, Aug 18 2014

STATUS

approved

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Last modified January 20 11:11 EST 2020. Contains 331083 sequences. (Running on oeis4.)