A122862 Numbers k such that (9*10^k - 11)/7 is prime.

2, 260, 650, 1928, 5768, 36548

Offset

1,1

Comments

All terms are of the form 2+6*i, i = 0,1,... .

Are there any k's such that (9*10^k - 11)/p is prime for prime p<>7?

Links

Table of n, a(n) for n=1..6.

Mathematica

Do[If[PrimeQ[(9*10^n-11)/7], Print[n]], {n, 2, 7220, 6}]

Prog

(PARI) is(n)=ispseudoprime((9*10^n-11)/7) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Cf. A100275.

Sequence in context: A089663 A252708 A103029 * A236437 A388297 A137105

Adjacent sequences: A122859 A122860 A122861 * A122863 A122864 A122865

Keyword

nonn,more

Author

Zak Seidov, Sep 22 2006

Extensions

a(6) from Michael S. Branicky, Jul 08 2025

Status

approved