This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A064858 #17 Jan 31 2025 03:29:36
%S A064858 1,2,3,4,30,60,14,840,315,504,6930,9240,180180,360360,30030,720720,
%T A064858 2042040,2450448,10581480,1989680,58198140,232792560,1338557220,
%U A064858 254963280,13385572200,26771144400,5736673800,6177956400,291136195350
%N A064858 Denominators of partial sums of reciprocals of lcm(1..n) = A003418(n).
%H A064858 Robert Israel, <a href="/A064858/b064858.txt">Table of n, a(n) for n = 1..2296</a>
%F A064858 a(n) = denominator(Sum_{j=1..n} 1/lcm(1..j)).
%e A064858 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.
%p A064858 R:= 1: m:= 1: for n from 2 to 100 do m:= ilcm(m,n); R:= R,1/m od:
%p A064858 P:= ListTools:-PartialSums([R]):
%p A064858 map(denom, P); # _Robert Israel_, Jan 30 2025
%t A064858 q[x_] := Apply[LCM, Table[j, {j, 1, x}]] Table[Denominator[Apply[Plus, Table[1/q[w], {w, 1, m}]]], {m, 1, 30}]
%Y A064858 Cf. A003418, A064857, A064859.
%K A064858 nonn,frac
%O A064858 1,2
%A A064858 _Labos Elemer_, Oct 08 2001