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 A068565 #13 Jun 26 2019 11:03:30
%S A068565 2,8,3,192,960,1920,1680,215040,645120,64512,1419264,11354112,
%T A068565 147603456,295206912,46126080,47233105920,802962800640,802962800640,
%U A068565 15256293212160,61025172848640,61025172848640,122050345697280
%N A068565 Denominators of Sum_{k=1..n} 1/(k * 2^k).
%C A068565 Sum_{k>=1} 1/(k * 2^k) = log(2).
%o A068565 (PARI) a(n) = denominator(sum(k=1, n, 1/(k * 2^k))); \\ _Michel Marcus_, Jun 26 2019
%Y A068565 Cf. A068566.
%K A068565 easy,frac,nonn
%O A068565 1,1
%A A068565 _Benoit Cloitre_, Mar 25 2002