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Search: id:A124056
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| A124056 |
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a(1)=1. a(n) = number of terms from among the first (n-1) terms of the sequence which divide a(n-1). |
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1
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| 1, 1, 2, 3, 3, 4, 4, 5, 3, 5, 4, 6, 7, 3, 6, 9, 7, 4, 7, 5, 5, 6, 10, 8, 8, 9, 8, 10, 9, 9, 10, 10, 11, 3, 7, 6, 12, 17, 3, 8, 11, 4, 8, 13, 3, 9, 14, 8, 14, 9, 15, 14, 10, 12, 21, 14, 11, 5, 7, 7, 8, 15, 16, 16, 17, 4, 9, 16, 19, 3, 10, 14, 14, 15, 18, 23, 3, 11, 6, 17, 5, 8, 17, 6, 18, 27, 19
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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First occurrence of k: 1, 3, 4, 6, 8, 12, 13, 24, 16, 23, 33, 37, 44, 47, 51, 63, 38, 75, 69, 101, 55, 91, 76, 132, 102, ..., . - Robert G. Wilson v, Nov 05 2006
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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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a(12) is 6. a(1)=1, a(2)=1, a(3)=2, a(4)=3, a(5)=3, a(9)=3 and a(12)=6 are the seven terms that divide 6. So a(13)= 7.
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MATHEMATICA
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f[s_] := Append[s, Count[Mod[s[[ -1]], s], 0]]; Nest[f, {1, 1}, 86] (* Robert G. Wilson v *)
a[1]= 1 L[1]= {1} a[n_]:=a[n]= Sum[If[Mod[a[n - 1], L[n - 1][[i]]]==0, 1, 0], {i, 1, n-1}] L[n_]:=L[n]= Table[a[i], {i, 1, n}] L[40] (Joel Lewis (jblewis(AT)fas.harvard.edu), Nov 05 2006)
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CROSSREFS
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Sequence in context: A029107 A063123 A086333 this_sequence A030396 A064066 A060607
Adjacent sequences: A124053 A124054 A124055 this_sequence A124057 A124058 A124059
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Nov 03 2006
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com) and Joel Lewis (jblewis(AT)fas.harvard.edu), Nov 05 2006
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