use strict;
my @result;
my $one = "a" =~ /./;

sub add {
  my($vA,$vB) = @_;
  ($vA,$vB) = ($vA^$vB,($vA&$vB)<<$one) while $vB;
  return $vA;
}

my $val = $one;
do {
  push @result, $val;
  $val = add($val,$one);
} until $one.$one eq $val;