# Two terms approximation of a recurrence [closed]

Find an approximation up to the second term of $z_n$ where $z_{n+2}=z_{n+1}+\sqrt{n}z_{n}$ and $z_{2}=2z_{1}>0$.

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math.stackexchange.com/questions/163889/… –  user2468 Jul 10 '12 at 19:28