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A064858
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Denominators of partial sums of reciprocals of LCM[1..n]=A003418(n).
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2
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1, 2, 3, 4, 30, 60, 14, 840, 315, 504, 6930, 9240, 180180, 360360, 30030, 720720, 2042040, 2450448, 10581480, 1989680, 58198140, 232792560, 1338557220, 254963280, 13385572200, 26771144400, 5736673800, 6177956400, 291136195350
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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FORMULA
| a(n)=Sum{1/LCM[1...n], j=1..n}; denominator
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EXAMPLE
| 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) = 14.
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MATHEMATICA
| q[x_] := Apply[LCM, Table[j, {j, 1, x}]] Table[Denominator[Apply[Plus, Table[1/q[w], {w, 1, m}]]], {m, 1, 30}]
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CROSSREFS
| Cf. A003418, A064857, A064859.
Sequence in context: A059614 A028426 A024633 * A007114 A191471 A064889
Adjacent sequences: A064855 A064856 A064857 * A064859 A064860 A064861
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KEYWORD
| nonn,frac
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Oct 08 2001
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