Investigating the behaviour of a recursively defined sequence
Problem 197
Published on Friday, 6th June 2008, 10:00 pm; Solved by 2825Given 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.