Smoothly Increasing

An array $B$ of length $M$ is said to be *smoothly increasing* if it satisfies either of the following conditions: - $M = 1$, or - $B_1 \lt B_2 \lt \cdots \lt B_M$, and the difference array $[B_2 - B_1, B_3 - B_2, \ldots, B_M - B_{M-1}]$ is *smoothly increasing*. That is, an array is smoothly increasing if it either has length $1$, or it is strictly increasing and its difference array is smoothly