a(n) = n - 13.

Terms

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