A064889 - OEIS

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A064889

Denominators of partial sums of reciprocals of A051451 (A051451 includes lcm(1,...,x), x=power of prime from A000961 and also contains 1).

1, 2, 3, 4, 30, 420, 840, 1260, 9240, 9009, 240240, 471240, 232792560, 535422888, 26771144400, 181704600, 4822131600, 36100888223400, 3702655202400, 76327592243760, 737576396429600, 362291852261631600, 6416241209619040800

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..23.

FORMULA

a(n) = denominator(Sum_{k=1..n} 1/A051451(k)).

EXAMPLE

n=6, sum = (1/1) + (1/2) + (1/6) + (1/12) + (1/60) + (1/420) = 743/420, the denominator = a(6) = 743. Remark: If 1 is omitted from A051451, the denominators of partial sums of reciprocals do not change; however, numerators are changing, not compatible with these denominators (see A064888).

CROSSREFS

Cf. A051451, A003418, A000961, A064857, A064858, A064859, A064888, A064890.

Sequence in context: A354729 A305205 A356905 * A351999 A356885 A057917

Adjacent sequences: A064886 A064887 A064888 * A064890 A064891 A064892

KEYWORD

frac,nonn

AUTHOR

Labos Elemer, Oct 11 2001

STATUS

approved