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 A166081 Natural numbers that not are the sum of two distinct primes. 6

%I

%S 1,2,3,4,6,11,17,23,27,29,35,37,41,47,51,53,57,59,65,67,71,77,79,83,

%T 87,89,93,95,97,101,107,113,117,119,121,123,125,127,131,135,137,143,

%U 145,147,149,155,157,161,163,167,171,173,177,179,185,187,189,191,197,203

%N Natural numbers that not are the sum of two distinct primes.

%C All numbers that appear in A014092 are also in this sequence, by definition.

%C It seems that, for n > 6, the reverse is also true, however this is unproved. - _Ely Golden_, Dec 25 2016

%C All numbers that appear in this sequence but not A014092 must be even semiprimes with no other partitions into primes. - _Ely Golden_, Dec 25 2016

%H G. C. Greubel, <a href="/A166081/b166081.txt">Table of n, a(n) for n = 1..1000</a>

%F {1} U A025584 U A109934. - _R. J. Mathar_, Oct 08 2009

%F A000027 \ A038609. - _R. J. Mathar_, Oct 14 2009

%t Select[Range@ 204, Length@Select[Transpose@{#, Reverse@ # - 1} &@ Range[#] &@ #, Times @@ Boole@ Map[PrimeQ, #] == 1 && First@ # != Last@ # &] == 0 &] (* _Michael De Vlieger_, Apr 24 2016 *)

%Y Cf. A000027, A000040, A006881, A014092.

%Y Cf. A066615. - _R. J. Mathar_, Oct 14 2009

%K nonn

%O 1,2

%A _Juri-Stepan Gerasimov_, Oct 06 2009

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Last modified January 20 14:13 EST 2019. Contains 319333 sequences. (Running on oeis4.)