title: Problem 989
date: 2026/03/22 10:00:00
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# [Problem 989](https://projecteuler.net/problem=989)
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[Xem đề gốc (tiếng Anh)](https://projecteuler.net/problem=989)

## **Tổng Fibonacci**

$f(n) = F_n + F_{n+1}$. Tính $\sum_{n=1}^{10^{14}} f(n) \pmod{10^9+7}$.

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