a(n) = 12*a(n-1) - a(n-2).

Terms

a(0) =1a(1) =6a(2) =71a(3) =846a(4) =10081a(5) =120126a(6) =1431431a(7) =17057046a(8) =203253121a(9) =2421980406a(10) =28860511751a(11) =343904160606