Good numbers

[David Broadhurst]

> Does anyone know the full definition of "good" numbers ?

from MathSciNet:

Let $S$ be the set of non-negative integers whose representation in the scale
of 4 does not contain the digits 2 or 3. A pair $(M,N)$ of non-negative
integers is called "good" if every non-negative integer can be represented
uniquely in the form $Ms\sb 1-Ns\sb 2$, where each $s\sb i$ is in $S$.