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%I #4 Dec 05 2013 19:57:01
%S 1,1,8,45,504,5040,86400,1247400,28828800,544864320,15850598400,
%T 370507737600,12996271411200,362038989312000,14867734494412800,
%U 480878287553664000,22629566473113600000,833522365093017600000
%N a(2) = 1 by definition; otherwise a(n) = A109347(n)/n.
%F 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).
%e a(3) = 2*3*4/3 = 8, a(6)= 3*4*5*7*8*9/6 = 5040.
%Y Cf. A110347.
%K easy,nonn
%O 1,3
%A _Amarnath Murthy_, Jul 21 2005
%E More terms from _Joshua Zucker_, May 08 2006
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