A082718 Numbers k such that (83*10^(k-1) + 61)/9 is a depression prime.

3, 7, 13, 111, 3609, 37785, 181545

Offset

1,1

Comments

Prime versus probable prime status and proofs are given in the author's table.

References

C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.

Links

Table of n, a(n) for n=1..7.

Patrick De Geest, PDP Reference Table - 929.

Makoto Kamada, Prime numbers of the form 922...229.

Index entries for primes involving repunits.

Formula

a(n) = A056265(n) + 2.

Example

k=13 -> (83*10^(13-1) + 61)/9 = 9222222222229.

Crossrefs

Cf. A082697-A082720, A056265, A068651.

Sequence in context: A309775 A038691 A237890 * A221211 A322301 A154821

Adjacent sequences: A082715 A082716 A082717 * A082719 A082720 A082721

Keyword

nonn,base,hard,more

Author

Patrick De Geest, Apr 13 2003

Extensions

a(6) from Patrick De Geest, Jun 26 2005

Edited by Ray Chandler, Oct 20 2010

Edited by Ray Chandler, Nov 04 2014

a(7) from De Geest's website and from Kamada data by Elmo R. Oliveira, Dec 13 2025

Status

approved