data/problems/258.yml
---
:id: 258
:name: A lagged Fibonacci sequence
:url: https://projecteuler.net/problem=258
:content: |+
A sequence is defined as:
- <var>g</var><sub><var>k</var></sub> = 1, for 0 ≤ <var>k</var> ≤ 1999
- <var>g</var><sub><var>k</var></sub> = <var>g</var><sub><var>k</var>-2000</sub> + <var>g</var><sub><var>k</var>-1999</sub>, for <var>k</var> ≥ 2000.
Find <var>g</var><sub><var>k</var></sub> mod 20092010 for <var>k</var> = 10<sup>18</sup>.