a(n) = (4*n^2 - 1)^2.

Terms

a(0) =1a(1) =9a(2) =225a(3) =1225a(4) =3969a(5) =9801a(6) =20449a(7) =38025a(8) =65025a(9) =104329a(10) =159201a(11) =233289a(12) =330625a(13) =455625a(14) =613089a(15) =808201a(16) =1046529a(17) =1334025a(18) =1677025a(19) =2082249a(20) =2556801a(21) =3108169a(22) =3744225a(23) =4473225a(24) =5303809a(25) =6245001a(26) =7306209a(27) =8497225a(28) =9828225a(29) =11309769