a(n) = 250*n - 10.

Terms

a(0) =240a(1) =490a(2) =740a(3) =990a(4) =1240a(5) =1490a(6) =1740a(7) =1990a(8) =2240a(9) =2490a(10) =2740a(11) =2990a(12) =3240a(13) =3490a(14) =3740a(15) =3990a(16) =4240a(17) =4490a(18) =4740a(19) =4990a(20) =5240a(21) =5490a(22) =5740a(23) =5990a(24) =6240a(25) =6490a(26) =6740a(27) =6990a(28) =7240a(29) =7490