n! n - 1 -------- - ----- (n + 1)! n!
factorial(n)/factorial(n + 1) - (n - 1)/factorial(n)
factorial(n)/factorial(n + 1) - (-1.0 + n)/factorial(n)
factorial(n)/factorial(n + 1) - (-1.0 + n)/factorial(n)
2 n! - n*(1 + n)! + (1 + n)! --------------------------- n!*(1 + n)!
(factorial(n)^2 - n*factorial(1 + n) + factorial(1 + n))/(factorial(n)*factorial(1 + n))
/ 2 \ -\- n! - (1 + n)! + n*(1 + n)!/ --------------------------------- n!*(1 + n)!
-(-factorial(n)^2 - factorial(1 + n) + n*factorial(1 + n))/(factorial(n)*factorial(1 + n))
1 - n n! ----- + -------- n! (1 + n)!
(1 - n)/factorial(n) + factorial(n)/factorial(1 + n)
-(-Gamma(n) + n*Gamma(1 + n) - Gamma(n)*Gamma(1 + n)) ------------------------------------------------------ Gamma(n)*Gamma(2 + n)
-(-gamma(n) + n*gamma(1 + n) - gamma(n)*gamma(1 + n))/(gamma(n)*gamma(2 + n))
2 n! - (-1 + n)*(1 + n)! ----------------------- n!*(1 + n)!
(factorial(n)^2 - (-1 + n)*factorial(1 + n))/(factorial(n)*factorial(1 + n))