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%I #12 Sep 16 2015 04:38:05
%S 7,11,19,23,31,43,47,67,79,83,107,127,151,167,199,211,227,239,251,271,
%T 283,307,359,419,431,439,443,467,479,523,547,563,587,599,643,647,719,
%U 743,827,859,883,887,947,991,1031,1039,1103,1171,1259,1303,1399,1423
%N Primes p such that (p^2 - 3p - 2)/2 is prime.
%C These primes are all of the form 4k+3 (cf. A002145, A080148). - _R. J. Mathar_, Jun 08 2007
%H Max Alekseyev, <a href="/A129842/b129842.txt">Table of n, a(n) for n=1..230</a>
%e For p = 31, one half of 31^2 - 3*31 - 2 equals 433, which is prime.
%p a:=proc(n) local b: b:=ithprime(n): if isprime((b^2-3*b-2)/2)=true then b else fi end: seq(a(n),n=1..300); # _Emeric Deutsch_, May 25 2007
%p isA129842 := proc(p) if isprime(p) then isprime((p^2-3*p-2)/2) ; else false ; fi ; end: for n from 1 to 880 do p := ithprime(n) : if isA129842(p) then printf("%d, ",p) ; fi ; od : # _R. J. Mathar_, Jun 08 2007
%t Select[Prime[Range[2, 224]], PrimeQ[(#^2 - 3*# - 2)/2] &] (* _Stefan Steinerberger_, Jun 23 2007 *)
%K nonn
%O 1,1
%A _J. M. Bergot_, May 22 2007
%E More terms from _Emeric Deutsch_ and _R. J. Mathar_, May 25 2007
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