a(n) = (14*n+1)^2.

Terms

a(0) =1a(1) =225a(2) =841a(3) =1849a(4) =3249a(5) =5041a(6) =7225a(7) =9801a(8) =12769a(9) =16129a(10) =19881a(11) =24025a(12) =28561a(13) =33489a(14) =38809a(15) =44521a(16) =50625a(17) =57121a(18) =64009a(19) =71289a(20) =78961a(21) =87025a(22) =95481a(23) =104329a(24) =113569a(25) =123201a(26) =133225a(27) =143641a(28) =154449a(29) =165649