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A094383
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Primes p such that d>0 exists and p-d, p-2*d and p-3*d are also primes.
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9
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23, 29, 41, 43, 53, 59, 79, 83, 97, 101, 103, 107, 113, 127, 131, 139, 149, 151, 157, 163, 167, 173, 181, 191, 193, 197, 199, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 281, 283, 293, 307, 311, 313, 317, 331, 347, 349, 353, 359, 367, 373, 383
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OFFSET
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1,1
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COMMENTS
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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
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LINKS
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EXAMPLE
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59=prime(17) -> 59-6=53=prime(16) -> 53-6=47=prime(15) ->
47-6=41=prime(13), therefore 59 is a term; also 59 -> 59-18=41=prime(13) ->
41-18=23=prime(9) -> 23-18=5=prime(3).
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MATHEMATICA
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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 *)
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PROG
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(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
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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