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 A123093 Numbers which are not the sum of two 3-almost primes. 0
 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 18, 19, 21, 22, 23, 25, 27, 29, 31, 33, 34, 37, 41, 43, 44, 49, 51, 59, 61, 66, 67, 85, 99, 101, 109, 163 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS 3-almost prime analog of A072966, numbers which are not the sum of two semiprimes. In general, it seems that almost all even numbers can be written as the sum of two k-almost primes for any positive integer k. - T. D. Noe, Nov 06 2006 LINKS FORMULA Complement of Sumset {A014612} + {A014612}. MATHEMATICA nn=10000; t3=Select[Range[2, nn], Plus@@Last/@FactorInteger[ # ]==3&]; t3sum=Table[0, {nn}]; Do[n=t3[[i]]+t3[[j]]; If[n<=nn, t3sum[[n]]=1], {i, Length[t3]}, {j, i, Length[t3]}]; Flatten[Position[t3sum, 0]] (* T. D. Noe, Nov 06 2006 *) CROSSREFS Cf. A014612. Sequence in context: A337379 A121684 A191853 * A191932 A044920 A330938 Adjacent sequences:  A123090 A123091 A123092 * A123094 A123095 A123096 KEYWORD easy,fini,full,nonn AUTHOR Jonathan Vos Post, Sep 27 2006 EXTENSIONS Edited by T. D. Noe, Nov 06 2006 STATUS approved

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Last modified September 19 21:42 EDT 2020. Contains 337184 sequences. (Running on oeis4.)