Problem

Source: SRMC 2012

Tags: number theory, greatest common divisor, binomial coefficients



Let n>1 be an integer. Determine the greatest common divisor of the set of numbers {(2n2i+1):0in1} i.e. the largest positive integer, dividing (2n2i+1) without remainder for every i = 0, 1, ..., n–1 . (Here \left( \begin{matrix} m \\ l \\ \end{matrix} \right)=\text{C}_{m}^{l}=\frac{m\text{!}}{l\text{!}\left( m-l \right)\text{!}} is binomial coefficient.)