(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
=(2^8-1)(2^8+1)-2^16
=2^16-1-2^16
=-1
(10+1)(10^2+1)(10^4+1)(10^8+1)...(10^32+1)
(10+1)(10^2+1)(10^4+1)(10^8+1).(10^32+1)
=1/9*(10-1)(10+1)(10^2+1)(10^4+1)(10^8+1)...(10^32+1)
=1/9*(10^2-1)(10^2+1)(10^4+1)(10^8+1)...(10^32+1)
==1/9*(10^4-1)(10^4+1)(10^8+1)...(10^32+1)
=...
=(10^64-1)/9