OFFSET
3,1
LINKS
G. C. Greubel, Table of n, a(n) for n = 3..150
FORMULA
a(n) = 4^(n-3)*(n-3)!*(2*n-3)!/(2*n-5)!.
MATHEMATICA
Table[4^(n-3) (n-3)! (2n-3)!/(2n-5)!, {n, 3, 20}] (* Harvey P. Dale, Nov 27 2011 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Johannes W. Meijer, Nov 10 2009
STATUS
approved