A110983 Integers k such that 5*10^k + 51 is prime.

1, 3, 4, 16, 430, 727, 1415, 2691, 3160, 3904, 5464, 19875, 65255, 68524

Offset: 1

Author

Julien Peter Benney (jpbenney(AT)ftml.net), Oct 04 2005

Keywords

• more
• nonn

Comments

See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "50051".

a(15) > 10^5. - Robert Price, Jan 28 2017

Examples

			k = 4 is a member because: 5*10^4+51 = 5*10000+51 = 50000+51 = 50051, which is prime.
		

Links

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

Crossrefs

Cf. A049054, A088274, A088275, A095688, A107083, A108049, A108050, A108052, A108054.

Programs

Mathematica

Select[Range[1, 1000], PrimeQ[5*10^# + 51] &] (* Julien Kluge, Dec 15 2016 *)

Extensions

a(11)-a(12) from Ray Chandler, Dec 23 2010

Prepended a(1)=1 by Robert Price, Jan 28 2017

a(13)-a(14) from Robert Price, Jan 28 2017