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A163507
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If p is the product of k1-th prime, k2-th prime,..,kr-th prime then set a(n)=k1*k2*..*kr; if p is the k-th prime then set=k; a(1)=0 by convention
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2
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0, 1, 2, 1, 3, 2, 4, 1, 4, 3, 5, 2, 6, 4, 6, 1, 7, 4, 8, 3, 8, 5, 9, 2, 9, 6, 8, 4, 10, 6, 11, 1, 10, 7, 12, 4, 12, 8, 12, 3, 13, 8, 14, 5, 12, 9, 15, 2, 16, 9, 14, 6, 16, 8, 15, 4, 16, 10, 17, 6, 18, 11, 16, 1, 18, 10, 19, 7, 18, 12, 20, 4, 21, 12, 18, 8, 20, 12, 22, 3, 16, 13, 23, 8, 21, 14
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| or (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,..) becomes (0, 1, 2, 1, 3, 2, 4, 1, 4, 3, 5,..)
Apart from the first term, the same as A003963. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 01 2009]
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EXAMPLE
| If 9=3*3=2th prime*2th prime, then a(9)=2*2=4.
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MAPLE
| A003963 := proc(n) pfs := ifactors(n)[2] ; mul ( numtheory[pi](op(1, d))^op(2, d), d=pfs) ; end: printf("0, ") ; for n from 2 to 600 do printf("%d, ", A003963(n)) ; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 01 2009]
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CROSSREFS
| Cf. A000027, A000040, A002808.
Sequence in context: A167430 A056892 A136523 * A003963 A003960 A124223
Adjacent sequences: A163504 A163505 A163506 * A163508 A163509 A163510
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KEYWORD
| nonn
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AUTHOR
| Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Jul 29 2009
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EXTENSIONS
| Corrected by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 01 2009
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