a(n) = (7*n + 1)^2.

Terms

a(0) =1a(1) =64a(2) =225a(3) =484a(4) =841a(5) =1296a(6) =1849a(7) =2500a(8) =3249a(9) =4096a(10) =5041a(11) =6084a(12) =7225a(13) =8464a(14) =9801a(15) =11236a(16) =12769a(17) =14400a(18) =16129a(19) =17956a(20) =19881a(21) =21904a(22) =24025a(23) =26244a(24) =28561a(25) =30976a(26) =33489a(27) =36100a(28) =38809a(29) =41616