title: Problem 617
date: 2017/12/30 16:00:00
---
***
# [Problem 617](https://projecteuler.net/problem=617)
***
[Xem đề gốc (tiếng Anh)](https://projecteuler.net/problem=617)

## **Dãy lũy thừa gương**

$f(n) = \sum_{k=1}^{n} k^{n-k+1}$. Tính $\sum_{n=1}^{10^6} f(n) \pmod{10^9+7}$.

***