We call an integer $k\geq 1$ good if for all $q\in\mathbb{Q}$ there are $a_1,\ldots, a_k\in \mathbb{Q}$ such that $$q = \prod_{i=1}^k a_i \times \big(\sum_{i=1}^k a_i\big).$$ Euler showed that $k=3$ is good.

Is the set of good positive integers infinite?