In mathematics, an arithmetic progression (AP) or arithmetic sequence is a sequence of numbers such that the difference between the consecutive terms is constant.
For instance, the sequence 5, 7, 9, 11, 13, 15 … is an arithmetic progression with common difference of 2.
![3, 5, 7, 9, 11, 13, \cdots](/Images/godic/202412/21/30e5d31fc0f478d348a7d53ce7f0f7e74749.png")
就是一个等差数列。 在这个数列中，从第二项起，每项与其前一项之差都等于2，即公差为2。