mathematics specialized调和级数 a list of numbers whose reciprocals (= numbers that, when multiplied by another number, result in 1) get bigger or smaller by the same amount
If an arithmetic progression begins with 3, 6, and 9, then its harmonic progression would begin with 1/3, 1/6, and 1/9. 如果一个等差数列以3、6和9开始，那么它的调和级数将以1/3、1/6和1/9开始。
The arithmetic progression of even numbers (2,4,6...) gives us a harmonic progression that begins with 1/2, 1/4, and 1/6.
Compare: arithmetic progression