%I #12 Sep 10 2014 16:54:52
%S 7,11,17,19,23,29,31,41,43,47,53,59,61,67,71,73,79,83,89,97,101,103,
%T 107,109,113,127,131,137,139,149,151,157,163,167,173,179,181,191,193,
%U 197,199,211,223,227,229,233,239,241,251,257,263,269,271,277,281,283
%N Primes p with property that there exists a number d>0 such that numbers p-d, p-2*d are primes.
%C Conjecture: only 5 primes are not in the sequence: 2, 3, 5, 13, 37.
%H Vincenzo Librandi, <a href="/A216495/b216495.txt">Table of n, a(n) for n = 1..9617</a>
%t prms = 2; fQ[p_] := Module[{d = 1}, While[prms*d < p && Union[PrimeQ[p - Range[prms]*d]] != {True}, d++]; prms*d < p]; Select[Prime[Range[2, PrimePi[283]]], fQ] (* _T. D. Noe_, Sep 08 2012 *)
%o (PARI) is(n)=my(t); forprime(p=2,n-4,if(isprime((t=(n-p)\2)+p) && isprime(2*t+p) && isprime(n), return(1))); 0 \\ _Charles R Greathouse IV_, Sep 10 2014
%Y Cf. A094383, A216497, A216498, A216468.
%K nonn
%O 1,1
%A _Alex Ratushnyak_, Sep 08 2012