harmonic series

...A series in which the difference between each term and the next term is constant, as in the first example above, is called an arithmetic series, and a series in which the ratio between each term and the next term is constant, as in the second example, is called a geometric series. Also, a series in which the reciprocals of each term in an arithmetic series are its terms is called a harmonic series. A series with a finite number of terms is called a finite series, and a series with an infinite number of terms is sometimes called an infinite series, but when people simply say series, they usually mean an infinite series. ...

*Some of the terms that refer to the "harmonic series" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…上の第1の例のように各項とその次の項との差が一定である級数を等差級数arithmetic seriesまたは算術級数といい，第2の例のように各項とその次の項との比が一定である級数を等比級数geometric seriesまたは幾何級数という。また，等差級数の各項の逆数を項とする級数を調和級数harmonic seriesという。項数が有限である級数を有限級数といい，項数が無限にある級数を無限級数ということがあるが，単に級数といえば，ふつうは無限級数を意味する。…

※「harmonic series」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報