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

1,3

Comments

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

Links

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

Example

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.

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}]

Crossrefs

Cf. A000040, A020481, A236566, A236568.

Sequence in context: A302387 A049613 A002373 * A103153 A162022 A318240

Adjacent sequences: A236566 A236567 A236568 * A236570 A236571 A236572

Keyword

nonn

Author

Zhi-Wei Sun, Jan 29 2014

Status

approved