(n+1)n(n-1)! = n(n+1)n! = n^2 * (n+1)
n!/(n-1) + n!/2!(n-2)! = n(n-1)!/(n-1) + n!n/(2(n-2)!) = nn!(n-1)!/(n-1) + n(n-1) = n(n + (n-1))
(n-1)n!+n(n-1)! = n-1 + 1 = n
((n-1)!n(n+1))/n!+(n+1)!/(n-1)! = (n(n+1))/n + (n+1)n = 2n+2
(n+1)n(n-1)! = n(n+1)n! = n^2 * (n+1)
n!/(n-1) + n!/2!(n-2)! = n(n-1)!/(n-1) + n!n/(2(n-2)!) = nn!(n-1)!/(n-1) + n(n-1) = n(n + (n-1))
(n-1)n!+n(n-1)! = n-1 + 1 = n
((n-1)!n(n+1))/n!+(n+1)!/(n-1)! = (n(n+1))/n + (n+1)n = 2n+2