A103802 - OEIS

A103802

Primes p such that 2p - 9 and 2p + 9 are both primes.

7, 11, 19, 31, 59, 61, 79, 101, 151, 179, 229, 311, 359, 389, 409, 521, 709, 719, 751, 809, 971, 1039, 1061, 1151, 1171, 1201, 1361, 1459, 1481, 1669, 1699, 1811, 1949, 1999, 2131, 2341, 2371, 2411, 2609, 2671, 2711, 2791, 2851, 3019, 3041, 3061, 3119

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..47.

FORMULA

p, 2p-9 and 2p+9 all are positive and are primes (hence we omit p=2).

MATHEMATICA

Select[Range[7, 6000], PrimeQ[ # ] && PrimeQ[2# + 9] && PrimeQ[2# - 9] &]

okQ[n_]:=Module[{c=2n}, PrimeQ[c+9]&&PrimeQ[c-9]]; Select[Prime[ Range[5, 500]], okQ] (* Harvey P. Dale, Apr 25 2011 *)

PROG

(Magma) [p: p in PrimesUpTo(3200)| IsPrime(2*p+9) and IsPrime(2*p-9) ]; // Vincenzo Librandi, Jan 28 2011

CROSSREFS

Sequence in context: A235806 A238501 A133425 * A038984 A165549 A055939

Adjacent sequences: A103799 A103800 A103801 * A103803 A103804 A103805

KEYWORD

nonn

AUTHOR

Zak Seidov, Feb 16 2005

STATUS

approved