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%I #17 Sep 10 2014 12:21:15
%S 23,29,41,43,53,59,79,83,97,101,103,107,113,127,131,139,149,151,157,
%T 163,167,173,181,191,193,197,199,223,227,229,233,239,241,251,257,263,
%U 269,271,281,283,293,307,311,313,317,331,347,349,353,359,367,373,383
%N Primes p such that d>0 exists and p-d, p-2*d and p-3*d are also primes.
%C Conjecture: only 25 primes are not in the sequence, namely 2, 3, 5, 7, 11, 13, 17, 19, 31, 37, 47, 61, 67, 71, 73, 89, 109, 137, 179, 211, 277, 337, 379, 499, 557. - _Alex Ratushnyak_, Sep 08 2012
%H Vincenzo Librandi, <a href="/A094383/b094383.txt">Table of n, a(n) for n = 1..1000</a>
%e 59=prime(17) -> 59-6=53=prime(16) -> 53-6=47=prime(15) ->
%e 47-6=41=prime(13), therefore 59 is a term; also 59 -> 59-18=41=prime(13) ->
%e 41-18=23=prime(9) -> 23-18=5=prime(3).
%t prms = 3; 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[383]]], fQ] (* _T. D. Noe_, Sep 08 2012 *)
%o (PARI) is(n)=my(t); forprime(p=2,n-6,if((n-p)%3==0 && isprime((t=(n-p)/3)+p) && isprime(2*t+p) && isprime(n), return(1))); 0 \\ _Charles R Greathouse IV_, Sep 10 2014
%Y Cf. A094382, A216495, A216496, A216497, A216498, A216468.
%K nonn
%O 1,1
%A _Reinhard Zumkeller_, Apr 28 2004
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