Problem 197: Investigating the behaviour of a recursively defined sequence

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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.

Test

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