a(n) = 50*n^2 - 1.

Terms

a(0) =49a(1) =199a(2) =449a(3) =799a(4) =1249a(5) =1799a(6) =2449a(7) =3199a(8) =4049a(9) =4999a(10) =6049a(11) =7199a(12) =8449a(13) =9799a(14) =11249a(15) =12799a(16) =14449a(17) =16199a(18) =18049a(19) =19999a(20) =22049a(21) =24199a(22) =26449a(23) =28799a(24) =31249a(25) =33799a(26) =36449a(27) =39199a(28) =42049a(29) =44999