a(n) = (1 - (-9)^n)/10.

Terms

a(0) =1a(1) =-8a(2) =73a(3) =-656a(4) =5905a(5) =-53144a(6) =478297a(7) =-4304672a(8) =38742049a(9) =-348678440a(10) =3138105961a(11) =-28242953648a(12) =254186582833