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A087695 Numbers n such that n + 3 and n - 3 are both prime. 20
8, 10, 14, 16, 20, 26, 34, 40, 44, 50, 56, 64, 70, 76, 86, 100, 104, 106, 110, 134, 154, 160, 170, 176, 194, 196, 226, 230, 236, 254, 260, 266, 274, 280, 310, 314, 334, 350, 356, 370, 376, 386, 436, 446, 460, 464, 506, 544, 560, 566, 574, 590, 596 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
A010051(a(n)-3) * A010051(a(n)+3) = 1. - Reinhard Zumkeller, Nov 17 2015
LINKS
FORMULA
a(n) = A046117(n) - 3.
MAPLE
ZL:=[]:for p from 1 to 600 do if (isprime(p) and isprime(p+6) ) then ZL:=[op(ZL), (p+(p+6))/2]; fi; od; print(ZL); # Zerinvary Lajos, Mar 07 2007
MATHEMATICA
lst={}; Do[If[PrimeQ[n-3]&&PrimeQ[n+3], AppendTo[lst, n]], {n, 10^3}]; lst (* Vladimir Joseph Stephan Orlovsky, Sep 08 2008 *)
Select[Range[600], AllTrue[#+{3, -3}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, May 06 2015 *)
PROG
(Haskell)
a087695 n = a087695_list !! (n-1)
a087695_list = filter
(\x -> a010051' (x - 3) == 1 && a010051' (x + 3) == 1) [2, 4 ..]
-- Reinhard Zumkeller, Nov 17 2015
(PARI) p=2; q=3; forprime(r=5, 1e3, if(q-p<7 && (q-p==6 || r-p==6), print1(p+3", ")); p=q; q=r) \\ Charles R Greathouse IV, May 22 2018
CROSSREFS
Sequence in context: A171689 A163628 A060864 * A322998 A368280 A262708
KEYWORD
easy,nonn
AUTHOR
Zak Seidov, Sep 27 2003
STATUS
approved

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Last modified February 26 12:54 EST 2024. Contains 370352 sequences. (Running on oeis4.)