a(n) = 10-n.

Terms

a(0) =10a(1) =9a(2) =8a(3) =7a(4) =6a(5) =5a(6) =4a(7) =3a(8) =2a(9) =1a(10) =0a(11) =-1a(12) =-2a(13) =-3a(14) =-4a(15) =-5a(16) =-6a(17) =-7a(18) =-8a(19) =-9a(20) =-10a(21) =-11a(22) =-12a(23) =-13a(24) =-14a(25) =-15a(26) =-16a(27) =-17a(28) =-18a(29) =-19