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%I #9 Mar 18 2018 04:08:05
%S 1,2,3,4,30,60,14,840,315,504,6930,9240,180180,360360,30030,720720,
%T 2042040,2450448,10581480,1989680,58198140,232792560,1338557220,
%U 254963280,13385572200,26771144400,5736673800,6177956400,291136195350
%N Denominators of partial sums of reciprocals of lcm(1..n) = A003418(n).
%F a(n) = denominator(Sum_{j=1..n}} 1/lcm(1..n)).
%e 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.
%t q[x_] := Apply[LCM, Table[j, {j, 1, x}]] Table[Denominator[Apply[Plus, Table[1/q[w], {w, 1, m}]]], {m, 1, 30}]
%Y Cf. A003418, A064857, A064859.
%K nonn,frac
%O 1,2
%A _Labos Elemer_, Oct 08 2001
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