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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
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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
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OFFSET
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1,4
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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.
Adjacent sequences: A115748 A115749 A115750 this_sequence A115752 A115753 A115754
Sequence in context: A113309 A062362 A084113 this_sequence A048684 A109969 A085035
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), 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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