a(n) = n * 2^n * (n!)^2.A333772a(n) = n * 2^n * (n!)^2.Terms a(0) =2a(1) =32a(2) =864a(3) =36864a(4) =2304000a(5) =199065600a(6) =22759833600External referencesoeis: A333772