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Inverse of a Factorial

Factorial: x!=y , 3!=3*2*1=6

Inverse Factorial: x=inv!(y) , inv!(6)=3

Gamma function:gm(x)=(x-1)!

Equation:gm(x)=(x-1)!  solving you obtain inv!(gm(x))+1=x

Example:x=5 , inv!(gm(5))+1=x <> inv!(24)+1=5  <> y+1=5 <> y=4 

4!=4*3*2*1=24

Based on this , the inverse formula of gamma function is invgm(x)=inv!(x)+1

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