Dave,
I don't think that would work, because you'd never get AA*. The first TLA would be ABC.
Blue,
It isn't very elegant, but try this:
$List = "A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"
$k = $list.count
$res = @()
for ($h=0; $h...