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Numbers n such that (n^2-8)/8 is prime.
5

%I #19 Aug 31 2017 18:52:19

%S 8,12,16,24,28,32,40,44,52,60,68,72,84,88,96,100,112,136,144,152,156,

%T 164,168,172,180,184,196,200,208,224,236,248,252,256,276,292,304,320,

%U 324,340,348,364,368,380,392,408,432,436,448,452,460,472,500,504,508

%N Numbers n such that (n^2-8)/8 is prime.

%C These numbers need to be of the form 4*j then (16*j^2-8)/8 = 2*j^2-1.

%C A066436 gives resulting primes p such that 8p+8 is square. - _Ray Chandler_, Sep 15 2005

%H G. C. Greubel, <a href="/A110558/b110558.txt">Table of n, a(n) for n = 1..5000</a>

%F a(n) = 2*A090697(n) = 4*A066049(n). - _Ray Chandler_, Sep 15 2005

%t Select[Range[510],PrimeQ[(#^2-8)/8]&] (* _Harvey P. Dale_, Feb 03 2011 *)

%o (PARI) is(n)=isprime((n^2-8)/8) \\ _Charles R Greathouse IV_, Feb 20 2017

%Y Cf. A066049, A066436, A090697, A091176.

%K nonn

%O 1,1

%A _Pierre CAMI_, Sep 12 2005

%E Extended by _Ray Chandler_, Sep 15 2005