a(n) = Stirling2(n, floor(n/2)) * floor(n/2)!.

Terms

a(0) =1a(1) =0a(2) =1a(3) =1a(4) =14a(5) =30a(6) =540a(7) =1806a(8) =40824a(9) =186480a(10) =5103000a(11) =29607600a(12) =953029440a(13) =6711344640a(14) =248619571200