time perl -wle '
$n = shift; die "need a number" unless $n and $n =~ /^\d+$/; 
$a = "a" x $n; $c = 0; $e = 26**$n; 
while () { push @x, $a; $a++ and $c++; last if $c == $e } 
print scalar @x' 4


##</code><code>##


time perl -MAlgorithm::Combinatorics=:all -wle '
$n = shift; die "need a number" unless $n and $n =~ /^\d+$/; 
@_ = ("a".."z"); $i = variations_with_repetition(\@_,$n); 
while ($c =  $i->next){
for  (@$c) { $x .= $_ } 
push @x, $x; undef $x } 
print scalar @x' 4