a(n) = 4-n.

Terms

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