a(n) = 20*n^2 - 1.

Terms

a(0) =19a(1) =79a(2) =179a(3) =319a(4) =499a(5) =719a(6) =979a(7) =1279a(8) =1619a(9) =1999a(10) =2419a(11) =2879a(12) =3379a(13) =3919a(14) =4499a(15) =5119a(16) =5779a(17) =6479a(18) =7219a(19) =7999a(20) =8819a(21) =9679a(22) =10579a(23) =11519a(24) =12499a(25) =13519a(26) =14579a(27) =15679a(28) =16819a(29) =17999