2^64-1
=(2^32+1)(2^32-1)
=(2^32+1)(2^16+1)(2^16-1)
=(2^32+1)(2^16+1)(2^8+1)(2^8-1)
=(2^32+1)(2^16+1)(2^8+1)(2^4+1)(2^4-1)
=15*17*(2^32+1)(2^16+1)(2^8+1),
2^48-1
=(2^24+1)(2^24-1)
=(2^24+1)(2^12+1)(2^12-1)
=(2^24+1)(2^12+1)(2^6+1)(2^6-1)
=65*63*(2^24+1)(2^12+1),
即2^48-1可以被65和63整除.