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 A375534 #22 Apr 10 2025 08:18:34
%S A375534 1,2,6,30,210,4830,140070,5182590,222851370,10474014390,555122762670,
%T A375534 32752242997530,2194400280834510,160191220500919230,
%U A375534 12655106419572619170,1050373832824527391110,93483271121382937808790,9067877298774144967452630,2022136637626634327741936490
%N A375534 a(n) = denominator of Sum_{i=1..n} 1/A038603(i).
%C A375534 See A375533 (the numerators) for further information.
%H A375534 Alois P. Heinz, <a href="/A375534/b375534.txt">Table of n, a(n) for n = 0..313</a>
%H A375534 N. J. A. Sloane, <a href="https://www.youtube.com/watch?v=3RAYoaKMckM">A Nasty Surprise in a Sequence and Other OEIS Stories</a>, Experimental Mathematics Seminar, Rutgers University, Oct 10 2024, Youtube video; <a href="https://sites.math.rutgers.edu/~zeilberg/expmath/sloane85BD.pdf">Slides</a> [Mentions this sequence]
%e A375534 The first few sums are 0/1, 1/2, 5/6, 31/30, 247/210, 5891/4830, 175669/140070, 6639823/5182590, ...
%t A375534 a[n_]:=Denominator[Sum[ 1/Part[ResourceFunction["OEISSequence"]["A038603"],i],{i,n}]]; Array[a,18] (* _Stefano Spezia_, Sep 06 2024 *)
%Y A375534 Cf. A002110, A038603, A375533, A375805.
%K A375534 nonn,frac
%O A375534 0,2
%A A375534 _N. J. A. Sloane_, Sep 06 2024
%E A375534 a(0)=1 prepended by _Alois P. Heinz_, Oct 21 2024