# An algebra problem by Anthony Pham

Algebra Level pending

There is a sequence of integers $$a_{1} ,a_{2},a_{3},\ldots$$ such that $$a_{n}=a_{n-1}-a_{n-2}$$, for every $$n>2$$. If the sum of the first 1996 terms is 2015, and the sum of the first 2015 terms is 1996, what is the sum of the first 2019 terms?

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