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 A262022 #12 Sep 14 2015 07:53:38
%S A262022 1,3,6,30,210,420,1260,13860,13860,180180,180180,360360,6126120,
%T A262022 116396280,23279256,23279256,535422888,535422888,13385572200,
%U A262022 40156716600,40156716600,1164544781400,36100888223400,72201776446800,72201776446800
%N A262022 Denominator of partial sums of a reordered alternating harmonic series.
%C A262022 See A262031 for this reordered alternating harmonic series with partial sums s(n).
%F A262022 a(n) = denominator(s(n)) with s(n) = Sum_{k=0..n} c(k), where c(k) = 3/(4*k+3), 3/(4*k+5), -3/(2*(k+1)) if k == 0, 1, 2 (mod 3), respectively.
%e A262022 See A262031 for s(n), n=0..11, and s(10^n) for n=0..6.
%o A262022 (PARI) lista(nn) = {my(s = 0); for (k=0, nn, if (k%3==2, t = -3/(2*(k+1)), if (k%3==1, t = 3/(4*k+5), t = 3/(4*k+3))); s += t; print1(denominator(s), ", "););} \\ _Michel Marcus_, Sep 13 2015
%Y A262022 Cf. A262031, A262023.
%K A262022 nonn,frac,easy
%O A262022 0,2
%A A262022 _Wolfdieter Lang_, Sep 08 2015