Perfect powers whose digits are in nondecreasing order.

Terms

a(0) =4a(1) =8a(2) =9a(3) =16a(4) =25a(5) =27a(6) =36a(7) =49a(8) =125a(9) =128a(10) =144a(11) =169a(12) =225a(13) =256a(14) =289a(15) =1156a(16) =1225a(17) =1369a(18) =1444a(19) =4489a(20) =6889a(21) =11236a(22) =11449a(23) =13456a(24) =13689a(25) =27889a(26) =33489a(27) =111556a(28) =112225a(29) =113569