Do not understand a concept in analysis of open-address hashing
For any $i$, $q_i = p_i + p_{i+1} + p_{i+2} + \dots$.  Now look at $\sum_{i\geq 1}q_i$ and how many times each $p_i$&nbsp;occurs.  $p_1$&nbsp;occurs only in&nbsp;$q_1$; $p_2$&nbsp;occurs in $q_1$ and&nbsp;$q_2$; and, in general, $p_i$&nbsp;occurs only in $q_1,\dots, q_i$.  In other words, each $p_i$&nbsp;occurs $i$&nbsp;times in the sum of the&nbsp;$q_i$s.