print +( 1<<(2**$_+$_-1) )-1 for 4,5,6;;
524287
68719476735
31

print unpack 'b*', pack 'Q', ( 1<<(2**$_+$_-1) )-1 for 4,5,6;;
1111111111111111111000000000000000000000000000000000000000000000
1111111111111111111111111111111111110000000000000000000000000000
1111100000000000000000000000000000000000000000000000000000000000