

A236569


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


2



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
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OFFSET

1,3


COMMENTS

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


LINKS

ZhiWei 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[2nPrime[k]], Print[n, " ", Prime[k]]; Goto[aa]], {k, 1, PrimePi[2n1]}];
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

ZhiWei Sun, Jan 29 2014


STATUS

approved



