Cahen's constant
In mathematics, Cahen's constant is defined as the value of an infinite series of unit fractions with alternating signs:
{\displaystyle C=\sum _{i=0}^{\infty }{\frac {^{i}}{s_{i}-1}}={\frac {1}{1}}-{\frac {1}{2}}+{\frac {1}{6}}-{\frac... Wikipedia