Question Number 10469 by FilupSmith last updated on 11/Feb/17

One definition of  Γ(x+1)  is:  Γ(x+1)=∫_0 ^( ∞) e^(−t) t^x dx     According to WolframAlpha, another  definition is:  Γ(x+1)=(1/(e^(2iπx) −1))∮_L e^(−t) t^x dx  Can someone explian to me where this  comes from and what it means.     Also, its been a long time since I learnt  contour integrals, so what does ∮_L  mean?