Perfect powers for which the two closest perfect powers are smaller.

Terms

a(0) =9a(1) =16a(2) =36a(3) =128a(4) =144a(5) =256a(6) =361a(7) =529a(8) =1024a(9) =1369a(10) =1764a(11) =2209a(12) =2809a(13) =3136a(14) =3481a(15) =5041a(16) =5929a(17) =6889a(18) =8281a(19) =9409a(20) =10816a(21) =12321a(22) =13924a(23) =16900a(24) =17689a(25) =19881a(26) =22201a(27) =24649a(28) =27225a(29) =29929