A178436 Numbers n such that 10^n - 77 is prime.

2, 4, 5, 14, 44, 64, 103, 282, 643, 670, 818, 1092, 1775, 1856, 4080, 4178, 4498, 6815, 8293, 10112, 12023, 13643

Offset: 1

Author

Robert Price, Dec 21 2010

Keywords

• more
• nonn

Comments

The next term, if one exists, is >100000. - Robert Price, Apr 25 2011

See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "99923".

Examples

			10^4 - 77 = 9923 which is a prime number.
		

Links

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

Crossrefs

Cf. A108330, A108328.

Programs

Mathematica

nMax=1000; Do[If[PrimeQ[10^n-77], Print[n]], {n, nMax}]

PARI

is(n)=ispseudoprime(10^n-77) \\ Charles R Greathouse IV, Jun 13 2017