A108320 Numbers k such that 609 * 10^k - 1 is prime.

1, 2, 3, 4, 5, 6, 12, 17, 43, 46, 50, 88, 110, 187, 472, 832, 834, 1034, 1311, 1700, 2756, 5470, 6124, 7404, 7891, 12010, 16411

Offset

1,2

Links

Table of n, a(n) for n=1..27.

Example

a(4) = 4 because 609*10^4-1 = 6089999, a prime.

Prog

(PARI) is(n)=ispseudoprime(609*10^n-1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Cf. A053580.

Sequence in context: A032989 A367147 A322570 * A177958 A032941 A273733

Adjacent sequences: A108317 A108318 A108319 * A108321 A108322 A108323

Keyword

more,nonn

Author

Jason Earls, Jun 30 2005

Extensions

a(27) from Michael S. Branicky, May 19 2023

Status

approved