Asymptotic equidistribution and convexity for partition ranks

We study the Dyson rank function $N(r,t;n)$, the number of partitions with rank congruent to $r$ modulo $t$. We first show that it is monotonic in $n$, and then show that it equidistributed as $n\to \mathrm{\infty }$. Using this result we prove a conjecture of Hou and Jagadeeson on the convexity of $N(r,t;n)$.