Generate list continued fractions for square root of number

gistfile1.py

from math import sqrt

def gcd(a,b):
    while a != 0:
        a, b = b % a, a
    return b

def sqrt_cf(D):
    A = []

    b = 0
    c = 1

    first_term = True
    ta,tb,tc = (0,0,0)

    while True:
        A_n = int( (sqrt(D) + b) / c ) 
        A.append(A_n)

        # Recurence set up by re-arranging:   A_n+1 = 1 / ( ((sqrt(D)+b)/c) - A_n )
        # and noting that the denominator is divisible by c
        
        (b,c) = ( (A_n*c-b),
                  (D - (b-A_n*c)**2)/c )
        
        if first_term:
            first_term = False
            tb,tc = b,c

        elif b==tb and c==tc:
            break
            
    return A


D = int(raw_input("D = "))
try:
    print "%s\t%s" % (D, sqrt_cf(D))
except:
    pass