[Math] ny formula for the series $1 + \frac12 + \frac13 + \cdots + \frac 1 n = ?$

algebra-precalculusharmonic-numberssequences-and-seriessummation

Is there any formula for this series?

$$1 + \frac12 + \frac13 + \cdots + \frac 1 n .$$

Best Answer

There is no formula for the nth partial sum of the harmonic series, only approximations. A well known approximation by Euler is that the nth partial sum is approximately $$\ln(n) + \gamma $$ where $\gamma$ is the Euler–Mascheroni constant and is close to $0.5772$. The amount of error in this approximation gets arbitrarily small for sufficiently large values of $n$.

A well known fact in mathematics is that the harmonic series is divergent which means that if you add up enough terms in the series you can make their sum as large as you wish.