Let
f(x) = x^2 - 4 if x < 7
f(x) = x + 13 if x >= 7
What is f(f(f(17)))?
$f(17) = 17 + 13 = 30$
$f(30) = 30 + 13 = 43$
$f(43) = 43 + 13 = \boxed{56}$
+876 
