%I A083688
%S A083688 4,144,360,33600,15120,34927200,2162160,172972800,1543782240,
%T A083688 10242872640,10346336,2338727174784,53542288800,4818805992000,
%U A083688 3228118134040800,1178332991611776000,78765574305600
%N A083688 Denominator of B(2n)*H(2n)/n*(-1)^(n+1) where B(k) is the k-th Bernoulli 
               number and H(k) the k-th harmonic number.
%H A083688 Ira Gessel, <a href="http://www.cs.brandeis.edu/~ira/papers/miki2.pdf">
               On Miki's identy for Bernoulli numbers</a> J. Number Theory 110 (2005), 
               no. 1, 75-82.
%F A083688 Miki's identity : B(n)*H(n)*(2/n) = sum(i=2, n-2, B(i)/i*B(n-i)/(n-i)*(1-C(n, 
               i)))
%o A083688 (PARI) a(n)=denominator((-1)^(n+1)*bernfrac(2*n)*sum(k=1,2*n,1/k)/n)
%Y A083688 Cf. A083687.
%Y A083688 Sequence in context: A119038 A048432 A122422 this_sequence A053899 A058414 
               A053891
%Y A083688 Adjacent sequences: A083685 A083686 A083687 this_sequence A083689 A083690 
               A083691
%K A083688 frac,nonn
%O A083688 1,1
%A A083688 Benoit Cloitre (benoit7848c(AT)orange.fr), Jun 15 2003