Project Euler Problem 197

Statement

Given is the function $f(x) = int(2^{30.403243784-x^{2}}) 10^{-9}$,
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.

Solution

I computed 1000 thousand times the sequence and I saw that it stabilized in 2 alternative values. I added them and that was the answe

f_x = lambda x: int(2 ** (30.403243784 - x ** 2)) * (10 ** -9)
 
if __name__ == '__main__':
    x_1 = -1
    for i in range(1000):
        x_2 = f_x(x_1)
        x_1 = f_x(x_2)
    print("The result is:", x_1 + x_2)

The Python file is available for download here.

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