A177508 Primes of the form 2*10^n-7.

13, 193, 1993, 19993, 1999993, 19999999999999993, 1999999999999999999993, 19999999999999999999999999993, 1999999999999999999999999999999999999999999999993, 19999999999999999999999999999999999999999999999999999999999999999999999999999999993

Offset

1,1

Links

Table of n, a(n) for n=1..10.

Mathematica

Select[2*10^Range[100]-7, PrimeQ] (* Harvey P. Dale, Jan 27 2015 *)

Prog

(Magma)[a: n in [1..250]|IsPrime(a) where a is (2*10^n-7)]

Crossrefs

Cf. A102946.

Sequence in context: A000563 A213698 A159196 * A228659 A221581 A015690

Adjacent sequences: A177505 A177506 A177507 * A177509 A177510 A177511

Keyword

nonn

Author

Vincenzo Librandi, Dec 11 2010

Extensions

One more term (a(10)) from Harvey P. Dale, Jan 27 2015

Status

approved