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A174179
Numbers n such that 10^n-2^n-1 is prime.
1
1, 3, 9, 15, 180, 747, 1065
OFFSET
1,2
COMMENTS
a(8) > 50000. - Jens Kruse Andersen, Aug 10 2014
PROG
(Magma) [n: n in [1..700] | IsPrime(10^n-2^n-1) ]
(PARI) is(n)=ispseudoprime(10^n-2^n-1) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
Cf. A173852.
Sequence in context: A015664 A272621 A134137 * A076362 A336970 A366051
KEYWORD
nonn,hard,more
AUTHOR
Vincenzo Librandi, Mar 11 2010
EXTENSIONS
a(6)-a(7) from Jens Kruse Andersen, Aug 10 2014
STATUS
approved