A225098 Numbers k such that k^2 - 2 and 2*k^2 - 1 are both prime.

2, 3, 7, 13, 15, 21, 43, 49, 63, 69, 127, 155, 183, 211, 231, 237, 259, 265, 273, 293, 301, 323, 335, 391, 435, 441, 447, 489, 505, 573, 595, 671, 713, 715, 743, 757, 797, 811, 951, 959, 973, 979, 987, 993, 1035, 1147, 1197, 1287, 1359, 1393, 1415, 1429, 1443, 1491, 1525, 1597, 1617, 1653

Offset: 1

Author

Gerasimov Sergey, Apr 27 2013

Keywords

• nonn

Comments

Primes in the sequence: 2, 3, 7, 13, 43, 127, 211, 293, 743, 757, 797, 811, 1429,...

Examples

			2^2 - 2 = 2 is prime and 2*2^2 - 1 = 7 is prime, so a(1) = 2.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Intersection of A028870 and A066049.

Programs

Mathematica

Select[Range[1653], PrimeQ[#^2 - 2] && PrimeQ[2*#^2 - 1] &] (* T. D. Noe, May 10 2013 *)

Extensions

Corrected by R. J. Mathar, May 05 2013