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Search: id:A141552
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| A141552 |
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Transformed products of prime factors of the composites, the largest prime and smallest prime incremented by 1. |
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+0
1
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| 9, 12, 18, 16, 18, 24, 24, 24, 36, 36, 36, 32, 36, 48, 36, 42, 48, 48, 54, 72, 48, 54, 48, 72, 60, 56, 72, 72, 72, 72, 72, 96, 64, 90, 72, 84, 108, 72, 96, 80, 90, 108, 96, 96, 144, 84, 108, 108, 96, 120, 144, 114, 120, 120, 96, 126, 144, 144, 126, 144, 108, 132, 120, 144
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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In the prime number decomposition of k=A002808(i), i=1,2,3,.., one instance of the largest prime, pmax=A052369(i), is replaced by pmax+1 and one instance of the smallest prime, pmin=A056608(i), is replaced by pmin+1. The product of this modified list of factors, k*(pmax+1)*(pmin+1)/(pmin*pmax), is added to the sequence.
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EXAMPLE
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k(1)=4=(p(max)=2)*(p(min)=2), transformed (2+1)*(2+1)=3*3=9=a(1).
k(2)=6=(p(max)=3)*(p(min)=2), transformed (3+1)*(2+1)=4*3=12=a(2).
k(6)=12=(p(max)=3)*(p=2)*(p(min)=2), transformed (3+1)*2*(2+1)=4*2*3=24=a(6), etc.
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CROSSREFS
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Cf. A141218, A141219, A141220, A141284.
Sequence in context: A076674 A027571 A154631 this_sequence A162822 A087269 A153973
Adjacent sequences: A141549 A141550 A141551 this_sequence A141553 A141554 A141555
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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), Aug 14 2008
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EXTENSIONS
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Edited and corrected by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 18 2008
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