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Numbers n such that prime(n)+prime(2n)+prime(3n) is prime.
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%I #12 Oct 04 2012 02:06:59

%S 2,3,12,14,17,18,19,27,29,30,31,33,34,35,36,41,43,48,49,56,57,63,66,

%T 71,77,78,79,80,92,95,102,106,108,109,113,116,118,121,125,130,134,141,

%U 142,146,147,158,162,164,168,179,182,184,187,190,194,201,204,209,211,214

%N Numbers n such that prime(n)+prime(2n)+prime(3n) is prime.

%H Vincenzo Librandi, <a href="/A068603/b068603.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[225],PrimeQ[Prime[#]+Prime[2#]+Prime[3#]]&] (* _Harvey P. Dale_, Jan 16 2011 *)

%K easy,nonn

%O 1,1

%A _Benoit Cloitre_, Mar 28 2002