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 A100650 #22 Aug 25 2025 10:13:14
%S A100650 1,2,3,3,30,30,35,35,210,210,1155,1155,10010,10010,15015,15015,510510,
%T A100650 510510,1616615,1616615,1939938,1939938,22309287,22309287,74364290,
%U A100650 74364290,111546435,111546435,6469693230,6469693230,33426748355,33426748355,200560490130,200560490130
%N A100650 Denominator of 1 - Sum_{i=1..n} Bernoulli(i).
%H A100650 Amiram Eldar, <a href="/A100650/b100650.txt">Table of n, a(n) for n = 0..2369</a>
%e A100650 1, 3/2, 4/3, 4/3, 41/30, 41/30, 47/35, 47/35, 289/210, 289/210, 1502/1155, 1502/1155, 15551/10010, 15551/10010, 5809/15015, 5809/15015, 3818123/510510, 3818123/510510, ...
%p A100650 A100650 := proc(n) 1-add( bernoulli(i),i=1..n) ; denom(%) ; end proc: # _R. J. Mathar_, Jul 01 2011
%t A100650 Denominator[1-Accumulate[BernoulliB[Range[0,40]]]] (* _Harvey P. Dale_, Feb 19 2015 *)
%o A100650 (PARI) a(n) = denominator(1 - sum(i=1, n, bernfrac(i))); \\ _Michel Marcus_, Feb 15 2021
%Y A100650 Cf. A002110, A100649 (numerators).
%K A100650 nonn,frac,changed
%O A100650 0,2
%A A100650 _N. J. A. Sloane_, Dec 05 2004