a(n) = (12*n + 7)^2.

Terms

a(0) =49a(1) =361a(2) =961a(3) =1849a(4) =3025a(5) =4489a(6) =6241a(7) =8281a(8) =10609a(9) =13225a(10) =16129a(11) =19321a(12) =22801a(13) =26569a(14) =30625a(15) =34969a(16) =39601a(17) =44521a(18) =49729a(19) =55225a(20) =61009a(21) =67081a(22) =73441a(23) =80089a(24) =87025a(25) =94249a(26) =101761a(27) =109561a(28) =117649a(29) =126025