OFFSET
0,4
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..450
FORMULA
E.g.f.: 1/(1-x)-1/sqrt(1-x^2).
If n is odd then a(n) = n! else a(n) = n!-((n-1)!!)^2.
MATHEMATICA
CoefficientList[Series[1/(1-x)-1/Sqrt[1-x^2], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Sep 21 2014 *)
PROG
(PARI) x='x+O('x^33); concat(0, Vec(serlaplace(1/(1-x)-1/sqrt(1-x^2)))) \\ Michel Marcus, Sep 21 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Yuval Dekel (dekelyuval(AT)hotmail.com), Oct 18 2003
EXTENSIONS
Formulae and more terms from Vladeta Jovovic, Oct 31 2003
Two more terms from Michel Marcus, Sep 21 2014
STATUS
approved