a(n) = 2*n*3^(2*n-1).

Terms

a(0) =0a(1) =6a(2) =108a(3) =1458a(4) =17496a(5) =196830a(6) =2125764a(7) =22320522a(8) =229582512a(9) =2324522934a(10) =23245229340a(11) =230127770466