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A174179 Numbers n such that 10^n-2^n-1 is prime. 1
1, 3, 9, 15, 180, 747, 1065 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(8) > 50000. - Jens Kruse Andersen, Aug 10 2014

LINKS

Table of n, a(n) for n=1..7.

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 A070066 A299636

Adjacent sequences:  A174176 A174177 A174178 * A174180 A174181 A174182

KEYWORD

nonn,hard,more

AUTHOR

Vincenzo Librandi, Mar 11 2010

EXTENSIONS

a(6)-a(7) from Jens Kruse Andersen, Aug 10 2014

STATUS

approved

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Last modified July 21 06:53 EDT 2019. Contains 325192 sequences. (Running on oeis4.)