a(n) = n^2 - 5.

Terms

a(0) =-5a(1) =-4a(2) =-1a(3) =4a(4) =11a(5) =20a(6) =31a(7) =44a(8) =59a(9) =76a(10) =95a(11) =116a(12) =139a(13) =164a(14) =191a(15) =220a(16) =251a(17) =284a(18) =319a(19) =356a(20) =395a(21) =436a(22) =479a(23) =524a(24) =571a(25) =620a(26) =671a(27) =724a(28) =779a(29) =836