The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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 Table of n, a(n) for n=1..13. 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 A059759 Adjacent sequences: A072963 A072964 A072965 * A072967 A072968 A072969 KEYWORD nonn AUTHOR Lior Manor Aug 13 2002 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 1 22:38 EDT 2023. Contains 365828 sequences. (Running on oeis4.)