For any strictly increasing sequence of natural numbers $ a_1...a_n $, is the expression given below transcendental? Stack Exchange gives a specific case Is $0.1010010001000010000010000001 \ldots$ transcendental? , with $ a_n=n$, as transcendent, but people I've asked don't think that can be generalized to all cases, likewise with using Liouville's inequality.
$ \sum_{n=1}^{\infty} \prod_{i=1}^{n} 10^{-a_i} $