Unlike many number sequences, this relies not on some mathematical property of the numbers themselves, but on their notation.

与许多数字序列不同，这不依赖于数字本身的某些数学属性，而是依赖于它们的符号。

These are the mathematical properties, or, in other words, the kinds of things that are measurable, such as length, breadth, and depth.

这些是数学属性，或者换句话说，是可测量的事物的种类，例如长度、宽度和深度。