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A072966
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Numbers which are not the sum of two semiprimes.
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10
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0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 17, 22, 33
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OFFSET
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1,3
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COMMENTS
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Is this sequence finite?
See the graph of sequence A072931 for compelling evidence that 33 is the last term of this sequence. - T. D. Noe, Apr 11 2007
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LINKS
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EXAMPLE
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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.
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MATHEMATICA
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lim = 10000;
s = Select[Range[lim], PrimeOmega[#] == 2 &];
c = Map[Total, Union[Subsets[s, {2}], Table[{s[[i]], s[[i]]}, {i, 1, Length[s]}]]];
Join[Complement[Range[0, lim], c], ">", lim ](* Robert Price, Mar 30 2019 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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