# Recurring Styles #7 - Perfect Squares!

$\large{y_{n+2} = (4k-5)y_{n+1} - y_n + 4 - 2k \ , \quad n \geq 1}$

Define the sequence $$(y_n)_{n=1}^\infty$$ above by $$y_1 = y_2 = 1$$. Find the sum of all integers $$k$$ such that every term of the sequence is a perfect square.

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