OFFSET
0,2
EXAMPLE
2*x - 3/2!*x^2 + 12/3!*x^3 - 66/4!*x^4 + 488/5!*x^5 ...
CROSSREFS
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
EXTENSIONS
a(0) inserted and title improved by Sean A. Irvine, Jul 27 2018
STATUS
approved