A174179 Numbers n such that 10^n-2^n-1 is prime.

1, 3, 9, 15, 180, 747, 1065

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 A336970 A366051

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