A082715 Numbers k such that (71*10^(k-1) - 17)/9 is a plateau prime.

3, 5, 87, 113, 171, 567, 1689, 8903, 115811

Offset: 1

Author

Patrick De Geest, Apr 13 2003

Keywords

• nonn
• base
• hard
• more

Comments

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

Examples

			k=5 -> (71*10^(5-1) - 17)/9 = 78887.
		

References

• C. Caldwell and H. Dubner, The near repdigit primes A(n-k-1)B(1)A(k), especially 9(n-k-1)8(1)9(k), Journal of Recreational Mathematics, Volume 28, No. 1, 1996-97, pp. 1-9.

Links

• Patrick De Geest, PDP Reference Table - 787.
• Makoto Kamada, Prime numbers of the form 788...887.
• Index entries for primes involving repunits.

Crossrefs

Cf. A082697-A082720, A056262.

Formula

a(n) = A056262(n) + 2.

Extensions

115811 from Ray Chandler, Aug 05 2011

a(2)=5 corrected by Patrick De Geest, Apr 28 2013

Edited by Ray Chandler, Nov 05 2014