a(n) = Product_{k=0..n-1} (n+k)!/(k+1)!.A107252a(n) = Product_{k=0..n-1} (n+k)!/(k+1)!.Terms a(0) =1a(1) =1a(2) =6a(3) =1440a(4) =36288000External referencesoeis: A107252