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A064858 Denominators of partial sums of reciprocals of lcm(1..n) = A003418(n). 3
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; text; internal format)
OFFSET
1,2
LINKS
FORMULA
a(n) = denominator(Sum_{j=1..n}} 1/lcm(1..n)).
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.
MATHEMATICA
q[x_] := Apply[LCM, Table[j, {j, 1, x}]] Table[Denominator[Apply[Plus, Table[1/q[w], {w, 1, m}]]], {m, 1, 30}]
CROSSREFS
Sequence in context: A028426 A024633 A326829 * A007114 A191471 A354729
KEYWORD
nonn,frac
AUTHOR
Labos Elemer, Oct 08 2001
STATUS
approved

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Last modified March 19 04:58 EDT 2024. Contains 370952 sequences. (Running on oeis4.)