A177866 Numbers n such that 10^n - 69 is prime.

2, 4, 6, 7, 8, 14, 20, 110, 138, 140, 145, 300, 390, 1484, 3194, 3300, 3950, 4986, 5574, 5630, 5874, 8866, 11390, 45130, 86110

Offset: 1

Author

Robert Price, Dec 28 2010

Keywords

• more
• nonn

Comments

The next term, if it exists, is > 100000.

See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "99931".

Examples

			10^6 - 69 = 999931 which is a prime number.
		

Links

• Table of n, a(n) for n = 1..25
• Makoto Kamada, List of near-repdigit-related prime numbers.
• Index entries for primes involving repunits.

Crossrefs

Cf. A108330, A108328.

Programs

Mathematica

m=1000; For[n=1, n
				

PARI

is(n)=ispseudoprime(10^n-69) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(24-25)=45130,86110 from Robert Price, May 29 2011