A082710 Numbers k such that (64*10^(k-1) + 53)/9 is a depression prime.

10907, 499211

Offset: 1

Author

Patrick De Geest, Apr 13 2003

Keywords

• nonn
• bref
• base
• hard
• more

Comments

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

Searched up to k=1200000 by Serge Batalov, Mar 02 2015

Examples

			a(1)=10907 -> (64*10^(10907-1) + 53)/9 = 7111...1117 or 10905 1's surrounded by two 7's.
		

References

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

Links

• Patrick De Geest, PDP Reference Table - 717.
• Makoto Kamada, Prime numbers of the form 711...117.
• Tanya Khovanova, Non Recursions
• C. Rivera and J.C. Rosa, Puzzle 197. Always composite numbers?

Crossrefs

Cf. A082697-A082720.

Extensions

Edited by Ray Chandler, Nov 05 2014

Additional PRP term 499211 by Serge Batalov, Mar 01 2015