The homeworks are getting overwhelming...I have NO IDEA where to start...I haven't taken a math class in 10 years (calculus II).

Let a-sub-n be the nth term f the sequence 1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6,..., constructed by including the integer k exactly k times. Show that a-sub-n = floor(sqrt(2n) + 1/2).

I honestly don't even know what the first step is or what I should even be thinking about...