A236569 Least term p of A236568 with 2*n - p prime, or 0 if such a prime p does not exist.

0, 0, 3, 3, 3, 5, 3, 3, 5, 3, 3, 5, 3, 5, 11, 3, 3, 5, 31, 3, 5, 3, 3, 5, 3, 5, 11, 3, 5, 31, 3, 3, 5, 31, 3, 5, 3, 3, 5, 43, 3, 5, 3, 5, 11, 3, 5, 43, 31, 3, 5, 3, 3, 5, 3, 3, 5, 3, 5, 11, 43, 11, 43, 31, 3, 5, 3, 5, 11, 3

Offset: 1

Author

Zhi-Wei Sun, Jan 29 2014

Keywords

• nonn

Comments

The conjecture in A236566 implies that a(n) > 0 for all n > 2.

Examples

			a(3) = 3 since prime(3 + 2) + 2 = 11 + 2 = 13 and 2*3 - 3 = 3 are both prime, but prime(2 + 2) + 2 = 9 is not.
		

Links

• Zhi-Wei Sun, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000040, A020481, A236566, A236568.

Programs

Mathematica

p[m_]:=PrimeQ[Prime[m+2]+2]
Do[Do[If[p[Prime[k]]&&PrimeQ[2n-Prime[k]],Print[n," ",Prime[k]];Goto[aa]],{k,1,PrimePi[2n-1]}];
Print[n," ",0];Label[aa];Continue,{n,1,100}]