von Mangoldt function

Etymology
Named after the German mathematician Hans von Mangoldt.

Proper noun

 * 1)  A certain arithmetic function that is neither multiplicative nor additive. It is denoted by Λ(n) and defined as :$$\Lambda(n) = \begin{cases} \log p & \mbox{if }n=p^k \mbox{ for some prime } p \mbox{ and integer } k \ge 1, \\ 0 & \mbox{otherwise.} \end{cases}$$