Someone asked me, and I told them I would try to find out... what is the meaning of this symbol:


B'L     or     BL'


(I'm not sure if the tick comes before or after the L. It was found on a "nerd clock". The value of this symbol, by the way, is 1.



What is the mathematical meaning of this symbol?
Apparently, it is supposed to be [Legendre's constant](http://en.wikipedia.org/wiki/Legendre%27s_constant), also known as $1$.


