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A092057
Primes of the form 2*p^2 - 1, where p is prime.
9
7, 17, 97, 241, 337, 577, 3361, 3697, 6961, 10657, 23761, 25537, 32257, 37537, 49297, 64081, 65521, 77617, 79201, 89041, 126001, 138337, 153457, 171697, 193441, 249217, 269377, 287281, 334561, 351121, 374977, 474337, 633937, 652081, 665857
OFFSET
1,1
MATHEMATICA
lst={}; Do[p=Prime[n]; If[PrimeQ[r=2*p^2-1], AppendTo[lst, r]], {n, 6!}]; lst (* Vladimir Joseph Stephan Orlovsky, Jun 20 2009 *)
Select[2#^2-1&/@Prime[Range[200]], PrimeQ] (* Harvey P. Dale, Jun 26 2017 *)
PROG
(PARI) for (i=1, 300, if(isprime(2*prime(i)^2-1), print1(2*prime(i)^2-1, ", ")))
CROSSREFS
Cf. A092058.
Cf. A106483 (primes p such that 2p^2 - 1 is also prime).
Sequence in context: A177123 A124165 A239150 * A082738 A092340 A181605
KEYWORD
easy,nonn
AUTHOR
Mohammed Bouayoun (mohammed.bouayoun(AT)sanef.com), Feb 19 2004
STATUS
approved