a(n) = 12*n^2 - 1.

Terms

a(0) =-1a(1) =11a(2) =47a(3) =107a(4) =191a(5) =299a(6) =431a(7) =587a(8) =767a(9) =971a(10) =1199a(11) =1451a(12) =1727a(13) =2027a(14) =2351a(15) =2699a(16) =3071a(17) =3467a(18) =3887a(19) =4331a(20) =4799a(21) =5291a(22) =5807a(23) =6347a(24) =6911a(25) =7499a(26) =8111a(27) =8747a(28) =9407a(29) =10091