perl -e 'for my $i (1..63) {if(int(log(2**($i-1))/log(2)) != $i-1) {print "$i\n"}}'

##</code><code>##

for my $i (1..63) {
    if(length(sprintf("%b",2**$i-1)) != length(sprintf("%b",2**($i-1)))) {
	print"$i\n";
	printf("%b\n",2**($i-1));
	printf("%b\n",(2**$i)-1);
    }
}