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A161539
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Numbers n such that composite (n) + n is a composite, where composite (n) denotes the n-th composite number.
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0
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2, 5, 6, 7, 9, 10, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 28, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 41, 42, 43, 46, 48, 49, 50, 51, 52, 53, 54, 55, 56, 59, 60, 61, 62, 63, 64, 65, 67, 68, 70, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 85, 86, 87, 88, 89
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| 2 is in the list because composite(2)+2 =6+2 = 8 and 8 is composite
5 is in the list because composite(5)+5 =10+5 = 15 and 15 is composite
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MATHEMATICA
| With[{comps=Complement[Range[2, 250], Prime[Range[PrimePi[250]]]]}, Transpose[Select[Thread[{Range[Length[comps]], comps}], !PrimeQ[ Total[#]]&]][[1]]] (* From Harvey P. Dale, Dec 02 2011 *)
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CROSSREFS
| A002808
Sequence in context: A050103 A187578 A193260 * A177859 A047580 A153384
Adjacent sequences: A161536 A161537 A161538 * A161540 A161541 A161542
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KEYWORD
| nonn
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AUTHOR
| Claudio L Meller (claudiomeller(AT)gmail.com), Jun 13 2009
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