## Investigating the behaviour of a recursively defined sequence

### Problem 197

Published on Friday, 6th June 2008, 10:00 pm; Solved by 2893

Given is the function f(x) = 230.403243784-x2 10-9 ( is the floor-function),
the sequence un is defined by u0 = -1 and un+1 = f(un).

Find un + un+1 for n = 1012.
Give your answer with 9 digits after the decimal point.