A102737 Numbers k such that 3*10^k - 11 is prime.

1, 4, 7, 11, 14, 16, 22, 29, 36, 40, 65, 139, 149, 204, 842, 1031, 1331, 1345, 1505, 1894, 3386, 3526, 11092, 23836, 37836, 138811, 182614

Offset: 1

Author

Tom Mueller (muel4503(AT)uni-trier.de), Feb 08 2005

Keywords

• more
• nonn

Comments

Some of the larger entries may only correspond to probable primes.

Numbers corresponding to terms <= 842 are certified primes. - Klaus Brockhaus, Feb 16 2005

Next term > 12500. - Ryan Propper, Jul 21 2006

For k > 1, numbers k such that the digit 2 followed by k-2 occurrences of the digit 9 followed by the digits 89 is prime. - Robert Price, Nov 25 2017

a(28) > 2*10^5. - Robert Price, Jul 04 2018

Links

• Makoto Kamada, Factorization of near-repdigit-related numbers.
• Makoto Kamada, Search for 29w89.

Programs

Mathematica

Select[Range[1,500],PrimeQ[3*10^# - 11]&] (* Julien Kluge, Sep 19 2016 *)

PARI

is(n)=ispseudoprime(3*10^n - 11) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(15)-a(19) from Klaus Brockhaus, Feb 16 2005

a(20)-a(23) from Ryan Propper, Jul 21 2006

a(24)-a(25) from Robert Price, Nov 25 2017

a(26) from Robert Price, Jul 04 2018

a(27) from Robert Price, Jul 25 2018