A111022 Integers n such that 8*10^n+21 is prime.

0, 1, 2, 4, 10, 40, 55, 162, 264, 506, 870, 948, 1339, 3587, 6428, 48490, 81487

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 "80021".

a(18) > 10^5. - Robert Price, Feb 06 2017

Examples

			n = 4 is a member because: 8*10^4+21 = 8*10000+21 = 80000+21 = 80021, 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, A110980.

Extensions

a(15) from Ray Chandler, Dec 23 2010

Prepended a(1)=0 and a(2)=1 by Robert Price, Feb 06 2017

a(16)-a(17) from Robert Price, Feb 06 2017