3.2

import sympy as sp

def solve_difference_equation():
n = sp.symbols('n')
x = sp.Function('x')
eq = sp.Eq(x(n + 2) - x(n + 1) - 2 * x(n), 0)
sol = sp.rsolve(eq, x(n), {x(0): -2, x(1): -2})
return sol

print(solve_difference_equation())
print("3022")