A train is used to transport four carriages in the order: ABCD. However, sometimes when the train arrives to collect the carriages they are not in the...
An infinite sequence of real numbers $a(n)$ is defined for all integers $n$ as follows: $$a(n) = \begin{cases} 1 & n \lt 0\\ \sum \limits_{i = 1}^{\infty}{\dfrac{a(n...