a(n) = n - 30.

Terms

a(0) =-30a(1) =-29a(2) =-28a(3) =-27a(4) =-26a(5) =-25a(6) =-24a(7) =-23a(8) =-22a(9) =-21a(10) =-20a(11) =-19a(12) =-18a(13) =-17a(14) =-16a(15) =-15a(16) =-14a(17) =-13a(18) =-12a(19) =-11a(20) =-10a(21) =-9a(22) =-8a(23) =-7a(24) =-6a(25) =-5a(26) =-4a(27) =-3a(28) =-2a(29) =-1