原式=2×(1-1/2)(1+1/2)(1+1/2^2)(1+1/2^4)(1+1/2^8)
=2×(1-1/2^2)(1+1/2^2)(1+1/2^4)(1+1/2^8)
=2×(1-1/2^4)(1+1/2^4)(1+1/2^8)
=2×(1-1/2^8)(1+1/2^8)
=2×(1-1/2^16)
=2-1/2^15
(1+1/2)(1+1/2^2)(1+1/2^4)(1+1/2^8)
=2*1/2(1+1/2)(1+1/2^2)(1+1/2^4)(1+1/2^8)
=2*(1-1/2)(1+1/2)(1+1/2^2)(1+1/2^4)(1+1/2^8)
=2*(1-1/2^16)
=2-1/2^15