OFFSET
1,2
COMMENTS
a(2n)*a(2n+1) = (4n+1)!. a(2)*a(3) = 5!, a(4)*a(5) = 9!.
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..350
FORMULA
a(1) = 1, a(2n) = (2n)!, a(2n-1) = (4n-3)!/(2n-2)!.
EXAMPLE
a(3) = 3*4*5 = 60, a(4)= 4*3*2*1 24.
MATHEMATICA
n = 1; anfunc[n_] := (If [OddQ[n], {an = n, Do[an = an*(n + i), {i, n - 1}]}, an = n! ]; an) Table[anfunc[n], {n, 1, 30}] - Elizabeth A. Blickley (Elizabeth.Blickley(AT)gmail.com), Mar 10 2006
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Amarnath Murthy, Nov 03 2005
EXTENSIONS
More terms from Elizabeth A. Blickley (Elizabeth.Blickley(AT)gmail.com), Mar 10 2006
STATUS
approved