A108493 Integers n such that 10^n-57 is prime.

2, 7, 10, 11, 17, 19, 39, 49, 50, 61, 95, 106, 187, 196, 849, 889, 6436, 7370, 14446, 19647, 34399, 39922, 81297, 84305

Offset: 1

Author

Julien Peter Benney (jpbenney(AT)ftml.net), Jul 06 2005

Keywords

• more
• nonn

Comments

Numbers corresponding to terms 849 and 889 are certified primes. (Primo 2.2.0 beta) - Ryan Propper, Jul 13 2005

No additional terms <100000.

See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "99943".

Examples

			n = 7 is a member because: 10^7-57 = 10000000-57 = 9999943, which is prime.
		

Links

• Makoto Kamada, List of near-repdigit-related prime numbers.
• Index entries for primes involving repunits.

Crossrefs

Cf. A089675, A095714, A092767, A108327, A108328, A108329, A108330, A108331, A108332, A177417.

Extensions

a(17)-a(19) from Kamada data by Robert Price, Dec 10 2010

a(20) from Kamada data by Robert Price, Dec 14 2010

a(21)-a(22) from Robert Price, Dec 15 2010

Edited by Ray Chandler, Dec 23 2010

a(23-24)=81297,84305 from Robert Price, May 29 2011