Summary: In a recent manuscript, Fox studied infinite subtraction games with a finite (ternary) and aperiodic Sprague-Grundy function. Here we provide an elementary example of a game with the given properties, namely the game given by the subtraction set ${F_{2n+1} - 1}$, where $F_{i}$ is the $i$th Fibonacci number, and $n$ ranges over the positive integers.

91A46, 11B39

subtraction game, Fibonacci number, sprague-Grundy function