OFFSET
0,5
FORMULA
a(n) = n!*sum(m=0..(n-1)/2, binomial((n-2)/2,m)*(-1)^(n-m-1)/(n-2*m)), n>0.
MATHEMATICA
With[{nn=30}, CoefficientList[Series[Log[1+Sin[ArcTan[x]]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Sep 19 2011 *)
PROG
(Maxima)
a(n):=n!*sum(binomial((n-2)/2, m)*(-1)^(n-m-1)/(n-2*m), m, 0, (n-1)/2);
CROSSREFS
KEYWORD
sign
AUTHOR
Vladimir Kruchinin, Jun 16 2011
STATUS
approved