A125272 - OEIS

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A125272

Primes p such that 3p - 2 and 3p + 2 are also primes.

3, 5, 7, 13, 23, 37, 43, 103, 127, 163, 167, 257, 293, 313, 337, 433, 523, 757, 797, 887, 953, 1013, 1063, 1153, 1283, 1303, 1307, 1483, 1597, 1657, 1667, 1693, 1723, 1783, 1913, 2003, 2333, 2347, 2557, 2897, 2927, 3067, 3533, 3823, 3943, 4003, 4013, 4093

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OFFSET

1,1

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A125215(n)/3.

MATHEMATICA

lst={}; Do[p=Prime[n]; If[PrimeQ[3*p-2]&&PrimeQ[3*p+2], AppendTo[lst, p]], {n, 7!}]; lst (* Vladimir Joseph Stephan Orlovsky, Jan 18 2009 *)

Select[Prime[Range[600]], AllTrue[3#+{2, -2}, PrimeQ]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, May 29 2021 *)

PROG

(Magma) [p: p in PrimesUpTo(70000)| IsPrime(3*p-2)and IsPrime(3*p+2)] // Vincenzo Librandi, Jan 29 2011

(PARI) is(n)=isprime(3*n-2)&&isprime(3*n+2)&&isprime(n) \\ Charles R Greathouse IV, Jul 02 2013

CROSSREFS

Intersection of A023208 and A088878.

Cf. A125215.

Sequence in context: A321671 A085013 A164939 * A127443 A003229 A077949

Adjacent sequences: A125269 A125270 A125271 * A125273 A125274 A125275

KEYWORD

nonn,easy

AUTHOR

Zak Seidov, Nov 26 2006

STATUS

approved