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 A232181 #17 Jul 17 2025 14:48:54
%S A232181 1,6,60,140,2520,27720,360360,360360,12252240,77597520,5173168,
%T A232181 118982864,8923714800,80313433200,2329089562800,72201776446800,
%U A232181 13127595717600,13127595717600,485721041551200,485721041551200,19914562703599200,122332313750680800
%N A232181 First bisection of harmonic numbers (denominators).
%C A232181 Denominator of H(2*n-1), where H(n) = Sum_{k=1..n} 1/k.
%F A232181 a(n) ~ exp(2n).
%t A232181 a[n_] := HarmonicNumber[2*n-1] // Denominator; Table[a[n], {n, 1, 25}]
%o A232181 (Magma) [Denominator(HarmonicNumber(2*n-1)): n in [1..30]]; // _Bruno Berselli_, Nov 20 2013
%Y A232181 Cf. A002805, A232180 (numerators).
%K A232181 nonn,frac,easy
%O A232181 1,2
%A A232181 _Jean-François Alcover_ and _Paul Curtz_, Nov 20 2013