While the large proportion of our genome that does not instruct our cells to form proteins has been harder to study than protein-coding genes, it has been shown to have vital physiological functions.

Peptoids, or n-substitued glycines, are complex and diverse oligomeric structures which have been explored for a number of biomimetic applications including drug delivery, surfactants, and catalysts.

In this article, we study some new characterizations of primitive recursive functions based on restricted forms of primitive recursion, improving the pioneering work of R. M. Robinson and M. D.