LECTURE NOTES IN ANALYSIS (2011)
《LECTURE NOTES IN ANALYSIS (2011)》 · 第 5 页 · Section 1.2「Divisibility」，Theorem 1.2 的证明
Consider the arithmetic progression $\ldots,b-3a,b-2a,b-a,b,b+a,b+2a,b+3a,\ldots$ extending indefinitely in both directions.