A123372 Numbers k such that 10*(11*10^k - 1) + 1 is prime.

0, 1, 29, 71, 95, 173, 298, 4937, 4982, 15755, 16639, 17621

Offset

1,3

Comments

a(13) > 50000. - Michael S. Branicky, Nov 10 2024

Links

Table of n, a(n) for n=1..12.

Example

a(1) = 0; 101 is prime.
a(2) = 1; 1091 is prime.
a(3) = 29; 10999999999999999999999999999991 is prime.

Mathematica

Select[Range[0, 1000], PrimeQ[10*(11*10^#-1)+1]&]

Prog

(PARI) g(n, m=1) = for(x=1, n, y=10*(11*10^x-1)+m; if(ispseudoprime(y), print1(x", ")))

Crossrefs

Sequence in context: A226892 A183194 A374613 * A031343 A155483 A141891

Adjacent sequences: A123369 A123370 A123371 * A123373 A123374 A123375

Keyword

hard,more,nonn

Author

Cino Hilliard, Oct 12 2006

Extensions

0 inserted and a(10)-a(12) from Ryan Hitchman, Sep 13 2017

Status

approved