See also Ackermann benchmark, Ackermann

Ackermann function - “The * function A defined inductively on pairs of nonnegative integers. The highly recursive nature of the function makes it a popular choice for testing the ability of * compilers or computers to handle * recursion. It provides an example of a function that is general * recursive but not * primitive recursive because of the exceedingly rapid growth in its value as m increases.” (Fair Use ODCS)

Ackermann function