

A141109


Even numbers 2n such that for every prime p in [n,2n2], 2np is also prime.


1



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



EXAMPLE

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


MATHEMATICA

t={}; Do[If[And@@PrimeQ[2nPrime[Range[PrimePi[n1]+1, PrimePi[2n2]]]], AppendTo[t, 2n]], {n, 2, 105}]; t


CROSSREFS



KEYWORD

fini,full,nonn


AUTHOR



STATUS

approved



