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A225098
Numbers k such that k^2 - 2 and 2*k^2 - 1 are both prime.
2
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
1,1
COMMENTS
Primes in the sequence: 2, 3, 7, 13, 43, 127, 211, 293, 743, 757, 797, 811, 1429,...
LINKS
EXAMPLE
2^2 - 2 = 2 is prime and 2*2^2 - 1 = 7 is prime, so a(1) = 2.
MATHEMATICA
Select[Range[1653], PrimeQ[#^2 - 2] && PrimeQ[2*#^2 - 1] &] (* T. D. Noe, May 10 2013 *)
CROSSREFS
Intersection of A028870 and A066049.
Sequence in context: A286176 A318401 A322703 * A101739 A363450 A336378
KEYWORD
nonn
AUTHOR
Gerasimov Sergey, Apr 27 2013
EXTENSIONS
Corrected by R. J. Mathar, May 05 2013
STATUS
approved