a(n) = (n-1)*n!*(n-1)!.A370847a(n) = (n-1)*n!*(n-1)!.Terms a(0) =0a(1) =2a(2) =24a(3) =432a(4) =11520a(5) =432000a(6) =21772800a(7) =1422489600a(8) =117050572800External referencesoeis: A370847