The smaller of a pair of successive cubefull numbers without a powerful number between them.

Terms

a(0) =27a(1) =125a(2) =243a(3) =625a(4) =1000a(5) =1944a(6) =2187a(7) =3375a(8) =4000a(9) =4913a(10) =10000a(11) =15552a(12) =16807a(13) =17496a(14) =27648a(15) =34992a(16) =50625a(17) =83349a(18) =107811a(19) =139968a(20) =157216a(21) =194481a(22) =250000a(23) =279841a(24) =389017a(25) =390224a(26) =405000a(27) =614125a(28) =628864a(29) =810000