a(n) = 25*n^2 - n.

Terms

a(0) =24a(1) =98a(2) =222a(3) =396a(4) =620a(5) =894a(6) =1218a(7) =1592a(8) =2016a(9) =2490a(10) =3014a(11) =3588a(12) =4212a(13) =4886a(14) =5610a(15) =6384a(16) =7208a(17) =8082a(18) =9006a(19) =9980a(20) =11004a(21) =12078a(22) =13202a(23) =14376a(24) =15600a(25) =16874a(26) =18198a(27) =19572a(28) =20996a(29) =22470