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Search: id:A166686
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| A166686 |
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If m-th composite is the product of k1-th prime, k2-th prime,.., kr-th prime and m+k1+k2+..+kr is prime then set a(n)=m. |
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1
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| 1, 2, 8, 9, 13, 14, 16, 17, 30, 31, 33, 34, 53, 59, 61, 65, 80, 85, 89, 92, 94, 96, 97, 103, 113, 116, 117, 121, 127, 128, 142, 143, 160, 163, 180, 182, 188, 189, 206, 208, 216, 221, 227, 235, 236, 242, 255, 256, 261, 262, 265, 271, 294, 297, 298, 300, 304, 315
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OFFSET
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1,2
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EXAMPLE
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Since 1th composite=4=2*2=(1th prime)*(1th prime) and 1+1+1=3(prime) then a(1)=1. Since 2th composite=6=2*3=(1th prime)*(2th prime) and 2+1+2=5(prime) then a(2)=2.
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CROSSREFS
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Cf. A000040, A002808.
Sequence in context: A057529 A120737 A081381 this_sequence A064833 A073606 A047353
Adjacent sequences: A166683 A166684 A166685 this_sequence A166687 A166688 A166689
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KEYWORD
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nonn
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AUTHOR
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Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Oct 18 2009
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EXTENSIONS
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6 removed, 49 removed, 94 inserted, 102 removed, 103 inserted by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 28 2009
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