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%I A072966 #15 Oct 16 2023 12:05:13
%S A072966 0,1,2,3,4,5,6,7,9,11,17,22,33
%N A072966 Numbers which are not the sum of two semiprimes.
%C A072966 Is this sequence finite?
%C A072966 See the graph of sequence A072931 for compelling evidence that 33 is the last term of this sequence. - _T. D. Noe_, Apr 11 2007
%e A072966 a(10) = 11 since there is no way to represent 11 as a sum of two semiprimes. 13 is not a term since 13 = 4 + 9.
%t A072966 lim = 10000;
%t A072966 s = Select[Range[lim], PrimeOmega[#] == 2 &];
%t A072966 c = Map[Total,Union[Subsets[s, {2}], Table[{s[[i]], s[[i]]}, {i, 1, Length[s]}]]];
%t A072966 Join[Complement[Range[0, lim], c], ">", lim ](* _Robert Price_, Mar 30 2019 *)
%Y A072966 Cf. A001358.
%K A072966 nonn
%O A072966 1,3
%A A072966 _Lior Manor_, Aug 13 2002

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