A063714 Values of r occurring in A063713.

3, 3, 5, 3, 3, 5, 3, 19, 5, 3, 7, 29, 3, 5, 3, 5, 3, 43, 5, 3, 7, 3, 7, 3, 5, 3, 11, 3, 5, 5, 3, 7, 89, 7, 3, 5, 3, 3, 5, 3, 13, 113, 7, 13, 127, 5, 3, 11, 137, 139, 5, 13, 3, 7, 3, 5, 5, 3, 7, 3, 13, 5, 19, 3, 3, 31, 197, 199, 7, 13, 17, 11, 3, 5, 3, 229, 5, 3, 11, 5, 11, 3, 19, 3, 7, 3, 7

Offset: 1

Author

Reinhard Zumkeller, Aug 10 2001

Keywords

• nonn
• look

Comments

This is not a mere union of A002373 and A020483 because of the minimality property of these sequences.

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A063713, A002373, A020483.

Programs

Maple

f:= proc(n) local k;
k:= 2;
  while k < 2*n do
   k:= nextprime(k);
    if isprime(2*n+k) and isprime(2*n-k) then return k fi
  od;
  NULL
end proc:
map(f, [$1..400]); # Robert Israel, Oct 09 2017

Mathematica

f[n_] := {AnyTrue[Prime[Range[PrimePi[2n-2]]], (r = #; PrimeQ[2n+r] && PrimeQ[2n-r])&], r}; Select[f /@ Range[200], #[[1]] =!= False &][[All, 2]] (* Jean-François Alcover, Feb 14 2018 *)