%I #4 Mar 30 2012 18:40:42
%S 1,4,35,240,3003,26880,415701,4435200,79676025,968647680,19535112675,
%T 263472168960,5837993287875,85816649318400,2058476433304725,
%U 32567418416332800,836589039864843825,14112547980410880000
%N A113551(n)/A006882(n).
%C a(n) is to A001700 as n!! is to n!.
%F a(n) = n * (n+2) * ... * ((3*n)-2) / n!!.
%e a(1) = (1)/(1) = 1.
%e a(2) = (2*4)/(2) = 4.
%e a(3) = (3*5*7)/(3*1) = 35.
%e a(4) = (4*6*8*10)/(4*2) = 240.
%e a(5) = (5*7*9*11*13)/(5*3*1) = 3003.
%e a(6) = (6*8*10*12*14*16)/(6*4*2) = 26880.
%Y Cf. A001700, A006882, A113551.
%K easy,nonn
%O 1,2
%A _Jonathan Vos Post_, Apr 10 2007
%E Corrected and extended by _Klaus Brockhaus_, Apr 15 2007