a(n) = 60*n^2 - 1.

Terms

a(0) =59a(1) =239a(2) =539a(3) =959a(4) =1499a(5) =2159a(6) =2939a(7) =3839a(8) =4859a(9) =5999a(10) =7259a(11) =8639a(12) =10139a(13) =11759a(14) =13499a(15) =15359a(16) =17339a(17) =19439a(18) =21659a(19) =23999a(20) =26459a(21) =29039a(22) =31739a(23) =34559a(24) =37499a(25) =40559a(26) =43739a(27) =47039a(28) =50459a(29) =53999