One of the most oft-cited coding questions especially in internship interviews is for the Fibonacci sequence. Here i provide different type of ways to generate Fibonacci numbers in Python including a generator

def fib_r(n):
        #print n
        if (n == 0): return(0)
        if (n == 1): return(1)
        return(fib_r(n-1) + fib_r(n-2))
        
    def fibBinet(n):
        phi = (1 + 5**0.5)/2.0
        return int(round((phi**n - (1-phi)**n) / 5**0.5))
        
    def fib_dp(n):
        l = [0,1]
        for i in range(2,n+1):
            l.append(l[i-1]+l[i-2])
        return l[n]
        
    def fib_ultimate(n):
        if n==0: return 0
        a,b = 0,1
        for i in range(n-1):
            a,b = b,a+b
        return b
        
    def fib_gen():
        a, b = 0, 1
        while True:            # First iteration:
            yield a            # yield 0 to start with and then
            a, b = b, a + b    # a will now be 1, and b will also be 1, (0 + 1)