In the text "Classical Real Analysis Second edition(2008)". The famed Cantor Tentary Set is defined in 1.). My initial question is how the Series is constructed/formulated in 1.) ?
$1.)$ $$ C = \Big\{ X \in [0,1]: X = \sum_{n=1}^{\infty}\frac{I_n}{j_n}\Big\} \, for \, I_n=0 \, \, or \, \, 2$$