A108653 Numbers k such that 10^k - 113 is prime.

3, 4, 16, 21, 31, 70, 124, 131, 203, 309, 791, 975, 1015, 4367, 4451, 8495, 23523, 30508, 41536, 41551, 43455, 43463, 51004

Offset

1,1

Comments

Next term, if it exists, is bigger than 3000. - Stefan Steinerberger, Feb 12 2006

Links

Table of n, a(n) for n=1..23.

Example

If n=3 then 10^n - 113 = 887 (prime).
If n=31 then 10^n - 113 = 9999999999999999999999999999887 (prime).

Mathematica

For[n=1, n<3000, n++, If[PrimeQ[10^n-113], Print[n]]] (* Stefan Steinerberger, Feb 12 2006 *)

Prog

(PARI) is(n)=ispseudoprime(10^n-113) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Sequence in context: A330299 A047164 A304988 * A316194 A123773 A290433

Adjacent sequences: A108650 A108651 A108652 * A108654 A108655 A108656

Keyword

hard,more,nonn

Author

Parthasarathy Nambi, Jul 06 2005

Extensions

a(6)-a(13) from Stefan Steinerberger, Feb 12 2006

a(14)-a(16) from Ryan Propper, Jan 09 2008

a(17) from Michael S. Branicky, Apr 01 2023

a(18)-a(23) from Michael S. Branicky, Oct 29 2024

Status

approved