a(n) = 46*n^2 - 1.

Terms

a(0) =45a(1) =183a(2) =413a(3) =735a(4) =1149a(5) =1655a(6) =2253a(7) =2943a(8) =3725a(9) =4599a(10) =5565a(11) =6623a(12) =7773a(13) =9015a(14) =10349a(15) =11775a(16) =13293a(17) =14903a(18) =16605a(19) =18399a(20) =20285a(21) =22263a(22) =24333a(23) =26495a(24) =28749a(25) =31095a(26) =33533a(27) =36063a(28) =38685a(29) =41399