A082703 Numbers k such that (18*10^(k-1) - 81)/9 is a plateau prime.

3, 5, 9, 41, 87, 201, 731, 1461, 23673, 28631

Offset: 1

Author

Patrick De Geest, Apr 13 2003

Keywords

• nonn
• base
• more

Comments

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

Examples

			k=9 -> (18*10^(9-1) - 81)/9 = 199999991.
		

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 - 191.
• Makoto Kamada, Prime numbers of the form 199...991.
• Index entries for primes involving repunits.

Crossrefs

Cf. A082697-A082720, A056250, A068649.

Formula

a(n) = A056250(n+1) + 2.

Extensions

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008

Edited by Ray Chandler, Nov 04 2014