a(n) = (3^(n-1))*(n!)^2.A080141a(n) = (3^(n-1))*(n!)^2.Terms a(0) =1a(1) =12a(2) =324a(3) =15552a(4) =1166400a(5) =125971200a(6) =18517766400External referencesoeis: A080141