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设ææ³¢é£å¥æ°åçé项为Anã
ï¼äºå®ä¸An = (p^n - q^n)/â5ï¼å
¶ä¸p = (â5 - 1)/2, q = (â5 + 1)/2ãä½è¿éä¸å¿
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Sn = A1 + A2 + ... + An
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An = Sn - S(n-1) = A(n-1) + A(n-2) = S(n-1) - S(n-2) + S(n-2) - S(n-3)
= S(n-1) - S(n-3)
å
¶ä¸åå¼ä¸ºS1 = 1, S2 = 2, S3 = 4ã
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Sn - 2S(n-1) + S(n-3) = 0
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x^3 - 2x^2 + 1 = 0
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(x - 1)(x^2 - x - 1) = 0
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x1 = 1
x2 = p
x3 = q
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Sn = c1 * x1^n + c2 * x2^n + c3 * x3^n
å
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