a(n) = (8/9)*(2+7*(-8)^(n-1)).

Terms

a(0) =1a(1) =8a(2) =-48a(3) =400a(4) =-3184a(5) =25488a(6) =-203888a(7) =1631120a(8) =-13048944a(9) =104391568a(10) =-835132528a(11) =6681060240a(12) =-53448481904a(13) =427587855248