login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A103802 Primes p such that 2p - 9 and 2p + 9 are both 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 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 14 22:42 EST 2019. Contains 329987 sequences. (Running on oeis4.)