OFFSET
1,3
FORMULA
a(2n+1) = (n+1)(n+2)...(2n-1)(2n)(2n+2) ...(3n+1)(3n+2). a(2n) = (1/2)(n+1)(n+2)...(2n-2)(2n-1)(2n+1)(2n+2)...(3n-1)(3n).
EXAMPLE
a(3) = 2*3*4/3 = 8, a(6)= 3*4*5*7*8*9/6 = 5040.
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Amarnath Murthy, Jul 21 2005
EXTENSIONS
More terms from Joshua Zucker, May 08 2006
STATUS
approved