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Search: id:A123093
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| A123093 |
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Numbers which are not the sum of two 3-almost primes. |
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| 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; listen)
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OFFSET
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1,2
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COMMENT
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3-almost prime analogue 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 (noe(AT)sspectra.com), Nov 06 2006
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FORMULA
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Complement of Sumset {A014612} + {A014612}.
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MATHEMATICA
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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 (noe(AT)sspectra.com), Nov 06 2006
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CROSSREFS
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Cf. A014612.
Sequence in context: A119675 A037144 A121684 this_sequence A044920 A022766 A097745
Adjacent sequences: A123090 A123091 A123092 this_sequence A123094 A123095 A123096
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KEYWORD
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easy,fini,full,nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), Sep 27 2006
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EXTENSIONS
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Edited by T. D. Noe (noe(AT)sspectra.com), Nov 06 2006
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