title: proof of the minimum number of nodes in an avl tree
body: <p>How do i prove that the minimum number of nodes in an avl tree of height <em>h</em> is
  <strong>(5+2*5^(1/2))*((((1+5^(1/2))/2)^h) + (5-2*5^(1/2))*((((1-5^(1/2))/2)^h)-1</strong>?</p>