%I #6 May 06 2017 23:40:42

%S 1,6,6,840,120,332640,5040,259459200,362880,335221286400,39916800,

%T 647647525324800,6227020800,1748648318376960000,1307674368000,

%U 6288139352883548160000,355687428096000,29051203810321992499200000

%N a(n) = product of n successive numbers up to n, if n is odd a(n) = n*(n-1)*.. = n!,if n is even a(n) = n(n+1)(n+2)... 'n' terms.

%C a(2n-1)*a(2n) = (4n-1)!. a(1)*a(2) = 3!, a(3)*a(4) = 7!.

%H G. C. Greubel, <a href="/A113550/b113550.txt">Table of n, a(n) for n = 1..350</a>

%F a(1) = 1, a(2n-1) = (2n-1)!, a(2n) = (4n-1)!/(2n-1)!.

%e a(3) = 3*2*1 = 6, a(4)= 4*5*6*7=840.

%t n = 1; anfunc[n_] := (If [EvenQ[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

%Y Cf. A113549.

%K easy,nonn

%O 1,2

%A _Amarnath Murthy_, Nov 03 2005

%E More terms from Elizabeth A. Blickley (Elizabeth.Blickley(AT)gmail.com), Mar 10 2006