OFFSET
0,3
MATHEMATICA
a[n_] := (-1)^(n+1)*Sum[1/(n*(2*k-1)), {k, 1, n}] // Denominator; Table[a[n], {n, 0, 19}] (* Jean-François Alcover, Nov 04 2013 *)
CROSSREFS
KEYWORD
nonn,easy,frac
AUTHOR
N. J. A. Sloane, Jun 17 2002
STATUS
approved