Euler's constant
Euler's constant is a mathematical constant, usually denoted by the lowercase Greek letter gamma, defined as the limiting difference between the harmonic series and the natural logarithm, denoted here by log:
Here, ⌊·⌋ represents the floor... Wikipedia
Discovered: 1734
First mention: De Progressionibus harmonicis observationes
Named after: Leonhard Euler; Lorenzo Mascheroni