# Problem 197: Investigating the behaviour of a recursively defined sequence

![graphic](img197.gif)

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.