What is the product of all roots of the function [math]\displaystyle f(x) = \sum_{n=1}^{6}(x-n)(x-n-1)(x-n-2)[/math]?
I have a recurrence: [math]X_n = X_{n-1} + 1 / (X_{n-1})[/math]. How do I get the value of n for which [math]X_n[/math] becomes at least [math]2*X_0[/math] where [math]X_0[/math] is a positive integer?