%I A058312
%S A058312 1,2,6,12,60,60,420,840,2520,2520,27720,27720,360360,360360,72072,
%T A058312 144144,2450448,2450448,46558512,232792560,232792560,232792560,
%U A058312 5354228880,5354228880,26771144400,26771144400,80313433200,11473347600
%N A058312 Denominator of the n-th alternating harmonic number, sum ((-1)^(k+1)/
               k, k=1..n).
%H A058312 T. D. Noe, <a href="b058312.txt">Table of n, a(n) for n=1..200</a>
%H A058312 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               HarmonicNumber.html">Harmonic Number</a>
%F A058312 G.f. for A058313(n)/ A058312(n) : log(1+x)/(1-x) - Benoit Cloitre (benoit7848c(AT)orange.fr), 
               Jun 15 2003
%e A058312 1, 1/2, 5/6, 7/12, 47/60, 37/60, 319/420, 533/840, 1879/2520, ...
%p A058312 A058313 := n->denom(add((-1)^(k+1)/k,k=1..n));
%o A058312 (PARI) a(n)=denominator(polcoeff(-log(1-x)/(x+1)+O(x^(n+1)),n))
%Y A058312 Numerators are A058313. Cf. A025530.
%Y A058312 Cf. A002805 (denominator of n-th harmonic number).
%Y A058312 Sequence in context: A117481 A083268 A085911 this_sequence A003418 A109935 
               A065887
%Y A058312 Adjacent sequences: A058309 A058310 A058311 this_sequence A058313 A058314 
               A058315
%K A058312 nonn,frac,nice,easy
%O A058312 1,2
%A A058312 N. J. A. Sloane (njas(AT)research.att.com), Dec 09 2000