A positive integer $n$ is defined as a \textit{stepstool number} if $n$ has one less positive divisor than $n + 1$. For example, $3$ is a stepstool number, as $3$ has $2$ divisors and $4$ has $2 + 1 = 3$ divisors. Find the sum of all stepstool numbers less than $300$.

Let's think step by step and output the final answer within \boxed{}.
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