a(n) = 48*n^2 - 1.

Terms

a(0) =-1a(1) =47a(2) =191a(3) =431a(4) =767a(5) =1199a(6) =1727a(7) =2351a(8) =3071a(9) =3887a(10) =4799a(11) =5807a(12) =6911a(13) =8111a(14) =9407a(15) =10799a(16) =12287a(17) =13871a(18) =15551a(19) =17327a(20) =19199a(21) =21167a(22) =23231a(23) =25391a(24) =27647a(25) =29999a(26) =32447a(27) =34991a(28) =37631a(29) =40367