A216495 Primes p with property that there exists a number d>0 such that numbers p-d, p-2*d are primes.

7, 11, 17, 19, 23, 29, 31, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283

Offset: 1

Author

Alex Ratushnyak, Sep 08 2012

Keywords

• nonn

Comments

Conjecture: only 5 primes are not in the sequence: 2, 3, 5, 13, 37.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..9617

Crossrefs

Cf. A094383, A216497, A216498, A216468.

Programs

Mathematica

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 *)

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