6.1.41 in http://www.math.sfu.ca/~cbm/aands/page_257.htm
or its related continued fraction
6.1.48 in http://www.math.sfu.ca/~cbm/aands/page_258.htm
that converges slowly (if at all) for small x, so it should be no surprise
that its accuracy improves as x becomes large.

Thanks Jerry for the links. Always an interesting subject. :)


(Side note...here's a test for larger x values)

In [A1]... then copied down:
=EXP(GAMMALN(ROW())) - FACT(ROW()-1)

<snip