On Tue, Jun 5, 2012 at 5:32 PM, Harvey P. Dale <hpd1 at nyu.edu> wrote: > Is the definition of the above sequence sufficient? If so, > why aren't 48, 80, 96, 112, etc. terms of the sequence? IIUC, the sequence consists of numbers n such that if a prime p divides n then so does p^4. 3 divides 48 but 3^4=81 doesn't, so 48 isn't a member. Doug