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Search: id:A123000
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| A123000 |
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a(1)=1. a(n) = smallest positive integer such that d(a(n))*d(a(n)+1) > d(a(n-1))*d(a(n-1)+1), where d(m) is the number of divisors of m. |
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1
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OFFSET
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1,2
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COMMENT
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a(n) also equals the smallest positive integer such that d(a(n)(a(n)+1)) > d(a(n-1)(a(n-1)+1)).
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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Since a(7) = 15, we want for a(8) the smallest positive integer m such that d(m)*d(m+1) > d(15)d(16) = 4*5=20. Checking: d(16)*d(17)=10, d(17)*d(18)=12, d(18)*d(19)=12, d(19)*d(20)=12. All of these are <= 20. But d(20)*d(21) = 6*4=24, which is > 20. So a(8) = 20.
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CROSSREFS
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Cf. A092517.
Sequence in context: A041101 A041809 A117566 this_sequence A132599 A082931 A034413
Adjacent sequences: A122997 A122998 A122999 this_sequence A123001 A123002 A123003
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KEYWORD
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more,nonn
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AUTHOR
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Leroy Quet Jul 06 2008
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