3(2^2+1)(2^4+1)(2^8+1)…(2^128+1)+1=?

3=2^2-1
代入3(2^2+1)(2^4+1)(2^8+1)…(2^128+1)+1
=（2^2-1）(2^2+1)(2^4+1)(2^8+1)…(2^128+1)+1
=（2^4-1）(2^4+1)(2^8+1)…(2^128+1)+1
.
.
=（2^128-1）(2^128+1)+1
=（2^128）²-1+1
=2^256