a(n) = n-26.

Terms

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