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Search: id:A064857
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| A064857 |
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Numerators of partial sums of reciprocals of LCM[1..n]=A003418(n). |
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+0
5
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| 1, 3, 5, 7, 53, 107, 25, 1501, 563, 901, 12389, 16519, 322121, 644243, 53687, 1288489, 3650719, 4380863, 18917363, 3557111, 104045497, 416181989, 2393046437, 455818369, 23930464373, 47860928747, 10255913303, 11044829711
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OFFSET
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1,2
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FORMULA
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a(n)=Sum{1/LCM[1...n], j=1..n}; numerator
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EXAMPLE
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n = 7: LCM values: 1, 2, 6, 12, 60, 60, 420; partial sum = 1+(1/2)+(1/6)+(1/12)+(1/60)+(1/60)+(1/420) = (420+210+70+35+7+7+1)/420 = 750/420 = 25/14, so a(7) = 25.
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MATHEMATICA
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q[x_] := Apply[LCM, Table[j, {j, 1, x}]] Table[Numerator[Apply[Plus, Table[1/q[w], {w, 1, m}]]], {m, 1, 30}]
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CROSSREFS
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Cf. A003418, A064858, A064859.
Sequence in context: A102742 A089044 A117646 this_sequence A065913 A137999 A056145
Adjacent sequences: A064854 A064855 A064856 this_sequence A064858 A064859 A064860
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KEYWORD
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nonn,frac
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Oct 08 2001
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