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A177508
Primes of the form 2*10^n-7.
0
13, 193, 1993, 19993, 1999993, 19999999999999993, 1999999999999999999993, 19999999999999999999999999993, 1999999999999999999999999999999999999999999999993, 19999999999999999999999999999999999999999999999999999999999999999999999999999999993
OFFSET
1,1
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
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, Dec 11 2010
EXTENSIONS
One more term (a(10)) from Harvey P. Dale, Jan 27 2015
STATUS
approved