Later, inspired by this wild and erratic behaviour of the fictional wild numbers, American mathematician J. C. Lagarias used the terminology to describe a precisely defined sequence of integers which shows somewhat similar wild and erratic behaviour.
Lagaria's wild numbers are connected with the Collatz conjecture and the concept of the 3x + 1 semigroup.
In mathematics, the multiplicative semigroup, denoted by W0, generated by the set
According to OEIS, "apparently these are completely fictional and there is no mathematical explanation".
However, the OEIS has some entries relating to pseudo-wild numbers carrying well-defined mathematical explanations.
[4] Even though the sequence of wild numbers is entirely fictional, several mathematicians have tried to find rules that would generate the sequence of the fictional wild numbers.
However, in the process, certain new sequences of integers were created having similar wild and erratic behavior.
A good example of this is the one discovered by the Dutch mathematician Floor van Lamoen.