1+2+2^2=？	Choose the correct choice from the following choices
A) (2^3-1)(2^3+1)  B) 2^6+1  C) 2^5-1  D) 2^5+1  E) 2^3-1
From 1+2+2^2=1(2^6-1)/(2-1)=2^3-1, the correct answer is 2^3-1.
<result>E</result>
1+2+2^2=？