For a geometric sequence {an}\{a_n\}{an} with a1=1a_1 = 1a1=1 and common ratio r=2r = 2r=2, if ∑n=1Nlog2(an)=15\displaystyle \sum_{n=1}^{N} \log_2(a_n) = 15n=1∑Nlog2(an)=15, what is NNN?
555
666
101010
151515