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A177508 Primes of the form 2*10^n-7. 0
13, 193, 1993, 19993, 1999993, 19999999999999993, 1999999999999999999993, 19999999999999999999999999993, 1999999999999999999999999999999999999999999999993, 19999999999999999999999999999999999999999999999999999999999999999999999999999999993 (list; graph; refs; listen; history; text; internal format)
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

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Last modified January 24 19:19 EST 2020. Contains 331211 sequences. (Running on oeis4.)