(2+1)(2^2+1)(2^4+1)(2^8+1)-2^16
=(2-1)(2+1)(2^2+1)(2^4+1)(2^8+1)-2^16
=(2^2-1)(2^2+1)(2^4+1)(2^8+1)-2^16
=(2^4-1)(2^4+1)(2^8+1)-2^16
=2^16-2^16
=0
(2+1)(2^2+1)(2^4+1)(2^8+1)-2^16
=(2-1)(2+1)(2^2+1)(2^4+1)(2^8+1)-2^16
=(2^2-1)(2^2+1)(2^4+1)(2^8+1)-2^16
=(2^4-1)(2^4+1)(2^8+1)-2^16
=2^16-2^16
=0