A082711 Numbers k such that (65*10^(k-1) + 43)/9 is a depression prime.

3, 5, 9, 29, 65, 725, 1787, 7277, 19463, 24215, 51779, 131393

Offset

1,1

Comments

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

a(13) > 2*10^5. - Tyler Busby, Feb 01 2023

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..12.

Patrick De Geest, PDP Reference Table - 727.

Makoto Kamada, Prime numbers of the form 722...227.

Index entries for primes involving repunits.

Formula

a(n) = A056257(n) + 2.

Example

k=9 -> (65*10^(9-1) + 43)/9 = 722222227.

Crossrefs

Cf. A082697-A082720, A056257.

Sequence in context: A262314 A338604 A209286 * A013622 A246666 A027715

Adjacent sequences: A082708 A082709 A082710 * A082712 A082713 A082714

Keyword

nonn,base,hard,more

Author

Patrick De Geest, Apr 13 2003

Extensions

Update from De Geest site by Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008

a(11)=51779 from Ray Chandler, Nov 16 2010

Edited by Ray Chandler, Nov 05 2014

a(12) from Tyler Busby, Feb 01 2023

Status

approved