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Search: id:A115751
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| A115751 |
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a(1)=1. a(n) = number of positive divisors of n which are not among the first (n-1) terms of the sequence. |
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+0
1
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| 1, 1, 1, 2, 1, 2, 1, 2, 2, 2, 1, 4, 1, 2, 3, 2, 1, 3, 1, 3, 2, 2, 1, 4, 2, 2, 2, 3, 1, 5, 1, 3, 2, 2, 2, 5, 1, 2, 2, 4, 1, 5, 1, 3, 3, 2, 1, 6, 2, 3, 2, 3, 1, 4, 2, 5, 2, 2, 1, 6, 1, 2, 4, 4, 2, 4, 1, 3, 2, 5, 1, 7, 1, 2, 3, 3, 2, 4, 1, 6, 3, 2, 1, 6, 2, 2, 2, 5, 1, 7, 2, 3, 2, 2, 2, 7, 1, 3, 4, 5, 1, 4, 1, 5, 4
(list; graph; listen)
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OFFSET
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1,4
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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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The divisors of 12 are 1, 2, 3, 4, 6 and 12. Of these, only the four divisors 3, 4, 6 and 12 do not occur among the first 11 terms of the sequence. So a(12) = 4.
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MAPLE
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with(numtheory): a[1]:=1: for n from 2 to 120 do div:=divisors(n): M:=convert([seq(a[j], j=1..n-1)], set): a[n]:=nops(div minus M): od: seq(a[n], n=1..120); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 01 2006
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CROSSREFS
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Cf. A088167.
Sequence in context: A113309 A062362 A084113 this_sequence A048684 A109969 A085035
Adjacent sequences: A115748 A115749 A115750 this_sequence A115752 A115753 A115754
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet, Mar 28 2006
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 01 2006
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