A137702 - OEIS

%I #9 Jun 15 2013 04:52:32

%S 5,13,73,421,541,613,661,673,1201,1453,2341,2473,2593,3061,3313,4441,

%T 4561,5113,6073,6121,6133,8521,8893,9601,9901,10453,11161,11701,12301,

%U 12721,13381,13681,13933,15241,15361,15373,15733,16033,16333,16381

%N Prime numbers p such that p +- ((p-1)/2) are primes.

%H Vincenzo Librandi, <a href="/A137702/b137702.txt">Table of n, a(n) for n = 1..1000</a>

%e (5-2, 5+2) are prime

%e (13-6, 13+6) are prime

%t Select[Prime[Range[1000]], PrimeQ[#-(#-1)/2] && PrimeQ[#+(#-1)/2]&]

%o (PARI) forprime(p=3,1e5,if(isprime(p+p\2)&isprime(p\2+1),print1(p", ")))

%Y Cf. A174734.

%K nonn,easy

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, Apr 27 2008