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A103802 Primes p such that both 2p +/- 9 are primes. 4
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

p, 2p-9 and 2p+9 all are positive 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) ] [From 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

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Last modified August 18 12:40 EDT 2017. Contains 290720 sequences.