a(0)=1, a(1)=6, a(n)=49*8^(n-2) if n>=2.

Terms

a(0) =1a(1) =6a(2) =49a(3) =392a(4) =3136a(5) =25088a(6) =200704a(7) =1605632a(8) =12845056a(9) =102760448a(10) =822083584a(11) =6576668672a(12) =52613349376a(13) =420906795008