a(n) = n-28.

Terms

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