a(n) = n*6^n.

Terms

a(0) =0a(1) =6a(2) =72a(3) =648a(4) =5184a(5) =38880a(6) =279936a(7) =1959552a(8) =13436928a(9) =90699264a(10) =604661760a(11) =3990767616a(12) =26121388032a(13) =169789022208