prc class

a class of total functions $\text{[math]}$ is called a primitive recursively closed (PRC) class if

the initial functions belong to $\text{[math]}$ ,
a function obtained from functions belonging to $\text{[math]}$ by either composition or recursion also belongs to $\text{[math]}$ .

[cite:;taken from @computability_davis_1994 chapter 3.3 prc classes]