A128455 - OEIS

A128455

Numbers k such that 9^k - 2 is a prime.

1, 2, 3, 11, 45, 51, 260, 324, 390, 393, 1112, 3092, 4445, 10373, 15861, 18528, 97715, 112961

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OFFSET

1,2

COMMENTS

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

LINKS

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).

Cf. A128472 (smallest prime of the form (2n-1)^k - 2 for k>(2n-1)).

KEYWORD

nonn,hard,more

AUTHOR

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