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A072966 Numbers which are not the sum of two semiprimes. 10
0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 17, 22, 33 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
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
LINKS
EXAMPLE
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.
MATHEMATICA
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 *)
CROSSREFS
Cf. A001358.
Sequence in context: A005577 A263362 A336733 * A363246 A245761 A371248
KEYWORD
nonn
AUTHOR
Lior Manor, Aug 13 2002
STATUS
approved

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Last modified March 28 11:46 EDT 2024. Contains 371241 sequences. (Running on oeis4.)