a(n) = 4*16^n - 2*4^n.

A193475

a(n) = 4*16^n - 2*4^n.

Terms

    a(0) =2a(1) =56a(2) =992a(3) =16256a(4) =261632a(5) =4192256a(6) =67100672a(7) =1073709056a(8) =17179738112a(9) =274877382656

External references