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%I #28 Jul 23 2016 09:24:32
%S 2,3,4,6,7,8,10,11,13,15,17,18,21,22,24,25,28,34,36,38,39,41,42,43,45,
%T 46,49,50,52,56,59,62,63,64,69,73,76,80,81,85,87,91,92,95,98,102,108,
%U 109,112,113,115,118,125,126,127,132,134,137,140,141,143,153,154,155
%N Numbers n such that 2*n^2 - 1 is a prime.
%C It is conjectured that this sequence is infinite.
%C A066436 gives resulting primes p such that (p+1)/2 is square. - _Ray Chandler_
%D D. Shanks, Solved and Unsolved Problems in Number Theory, 2nd. ed., Chelsea, 1978, p. 31.
%H T. D. Noe, <a href="/A066049/b066049.txt">Table of n, a(n) for n=1..1000</a>
%F a(n) = A090697(n)/2 = A110558(n)/4. - _Ray Chandler_, Sep 15 2005
%F a(n) = A160697(n+1). - _Reinhard Zumkeller_, May 24 2009
%t Select[Range[200],PrimeQ[2#^2-1]&] (* _Harvey P. Dale_, Jun 14 2011 *)
%o (PARI) { n=0; for (m=1, 10^9, if (isprime(2*m^2 - 1), write("b066049.txt", n++, " ", m); if (n==1000, return)) ) } \\ _Harry J. Smith_, Nov 08 2009
%Y Cf. A028870, A066436, A090697, A091176, A110558.
%K nonn
%O 1,1
%A _N. J. A. Sloane_, Jan 09 2002
%E Extended by _Ray Chandler_, Sep 15 2005
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