(d) Given, $n = 2006!$ $\therefore\ \frac{1}{\log_{2}n} + \frac{1}{\log_{3}n} + ... + \frac{1}{\log_{2006}n}$ $= \log_{n}{2 + \log_{n}{3 + ... + \log_{n}2006}}$ $= \log_{n}{(2.3.4.\ \ldots.2006)}$ $= \log_{n}{(2006!) = \log_{n}{n = 1}}$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.