Let f(x)=x*f(x-1)+f(x-2).
If f(0)=24 and f(1)=42 what is f(1000)?
Hmmm. Wolframalpha says this is a complicated mix of Bessel Functions. I typed in
rsolve [{a[n]==n*a[n-1]+a[n-2],a[0]=24,a[1]=42},a[n],n]
Sorry, my knowledge of recursive relations is a bit sparse.