A178437 Numbers n such that 10^n - 81 is prime.

2, 3, 17, 19, 31, 37, 43, 91, 339, 367, 407, 1135, 1175, 8653, 11987, 15793

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

Examples

			10^3 - 81 = 919 which is a prime number.
		

Links

• Makoto Kamada, Near-repdigit numbers of the form AA...AABA.
• Makoto Kamada, Prime numbers of the form 99...9919.
• Index entries for primes involving repunits.

Crossrefs

Cf. A108330, A108328.

Programs

Mathematica

nMax=1000; Do[If[PrimeQ[10^n-81], Print[n]], {n, nMax}]

PARI

is(n)=ispseudoprime(10^n-81) \\ Charles R Greathouse IV, Jun 13 2017