a(n) = 11^n-1.

Terms

a(0) =0a(1) =10a(2) =120a(3) =1330a(4) =14640a(5) =161050a(6) =1771560a(7) =19487170a(8) =214358880a(9) =2357947690a(10) =25937424600a(11) =285311670610