A087697 -id:A087697 - cp's OEIS frontend

A087682 Numbers n such that n + 8 and n - 8 are both prime.

11, 15, 21, 39, 45, 51, 75, 81, 105, 159, 165, 171, 189, 219, 231, 249, 285, 339, 345, 375, 381, 441, 471, 495, 549, 555, 579, 585, 609, 639, 651, 669, 735, 765, 819, 831, 945, 975, 1005, 1041, 1095, 1101, 1179, 1209, 1221, 1299, 1311, 1431, 1479, 1491

Offset: 1

Zak Seidov, Sep 27 2003

Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

Cf. A014574, A087678-A087683, A087695-A087697, A088768.

f[n_]:=PrimeQ[n-8]&&PrimeQ[n+8]; lst={};Do[If[f[n],AppendTo[lst,n]],{n,7,8!,2}];lst (* Vladimir Joseph Stephan Orlovsky, Oct 09 2009 *)

More terms from Ray Chandler, Oct 26 2003

A293271 Numbers n such that n - p and n + p are both prime for some prime p.

Original entry on oeis.org

5, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 26, 30, 32, 34, 36, 39, 40, 42, 44, 45, 46, 48, 50, 54, 56, 60, 64, 66, 69, 70, 72, 76, 78, 81, 84, 86, 90, 92, 96, 99, 100, 102, 104, 105, 106, 108, 110, 111, 114, 116, 120, 126, 129, 130, 132, 134, 138, 140, 142

Offset: 1

Gionata Neri, Oct 04 2017

nonn

Apart from a(1), all terms are composite.

Union of A087679 and 2*A063713. - Robert Israel, Oct 09 2017

Cf. A087679, A087695, A087696, A087697 (subsequences).

Cf. A063713.

filter:= proc(n) local k;
  k:= 1;
  while k < n do
    k:= nextprime(k);
    if isprime(n+k) and isprime(n-k) then return true fi
  od;
  false
end proc:
select(filter, [$1..1000]); # Robert Israel, Oct 09 2017

Select[Range@ 142, Function[n, AnyTrue[Prime@ Range@ PrimePi@ n, PrimeQ[n + {-#, #}] == {True, True} &]]] (* Michael De Vlieger, Oct 09 2017 *)

a(n) = forprime(p=1, n, i=n-p; j=n+p; if(isprime(i)&&isprime(j), n; break))

cp's OEIS Frontend

A087682 Numbers n such that n + 8 and n - 8 are both prime.

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