

A059803


Numbers n such that 9^n  8^n is prime or a strong pseudoprime.


13



2, 7, 29, 31, 67, 149, 401, 2531, 19913, 30773, 53857, 170099
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OFFSET

1,1


COMMENTS

Some of the larger entries may only correspond to probable primes.
In general, for any positive integers n, a and b, a>b, a necessary condition for a^nb^n to be prime is that either ab=1 and n be a prime or n=1 and ab be prime (from Arturo Magidin and Hagman in Sci.Math, Sep 11, 2010).  Vincenzo Librandi, Sep 12 2010


LINKS

Table of n, a(n) for n=1..12.


PROG

(PARI) is(n)=ispseudoprime(9^n8^n) \\ Charles R Greathouse IV, Jun 13 2017


CROSSREFS

Cf. A000043, A057468, A059801, A059802, A062572A062574, A062576A062666.
Sequence in context: A191478 A321181 A122118 * A076043 A180448 A116968
Adjacent sequences: A059800 A059801 A059802 * A059804 A059805 A059806


KEYWORD

nonn,hard


AUTHOR

Mike Oakes, Feb 23 2001


EXTENSIONS

Three more terms found by JeanLouis Charton in 20042005: a(9) = 30773, a(10) = 53857, a(11) = 170099.  Alexander Adamchuk, Dec 08 2006


STATUS

approved



