Achilles Number

An Achilles number is a positive integer that is powerful (in the sense that each prime factor occurs with exponent greater than one) but imperfect (in the sense that the number is not a perfect power). The first few are 72, 108, 200, 288, 392, 432, ... (OEIS A052486).

REFERENCES:

Sloane, N. J. A. Sequence A052486 in "The On-Line Encyclopedia of Integer Sequences."