A141109 Even numbers 2n such that for every prime p in [n,2n-2], 2n-p is also prime.

4, 6, 8, 10, 12, 14, 16, 18, 24, 30, 36, 42, 48, 60, 90, 210

Offset

1,1

Comments

The Deshouillers et al. paper proves that 210 is the last term. This sequence is the same as 2*A002271, but why?

Links

Table of n, a(n) for n=1..16.

Jean-Marc Deshouillers, Andrew Granville, Wladyslaw Narkiewicz and Carl Pomerance, An upper bound in Goldbach's problem, Math. Comp. 61 (1993), 209-213.

Example

30 is in this sequence because the primes p between 15 and 28 are {17,19,23} and 30-p is {13,11,7}.

Mathematica

t={}; Do[If[And@@PrimeQ[2n-Prime[Range[PrimePi[n-1]+1, PrimePi[2n-2]]]], AppendTo[t, 2n]], {n, 2, 105}]; t

Crossrefs

Sequence in context: A353537 A134928 A279040 * A333197 A289426 A186331

Adjacent sequences: A141106 A141107 A141108 * A141110 A141111 A141112

Keyword

fini,full,nonn

Author

T. D. Noe, Jun 03 2008

Status

approved