I have 
``` 
while n > 0:
    c = k * (c[1:] - c[:-1]) / (t[k + 1: -1] - t[1: -(k + 1)]) 
    t = t[1:-1] 
    k -= 1
    n -= 1 
``` 
but I've got restrictions on the knot points that are checked ahead of time. In particular, only isolated knots in the interior. Otherwise the derivatives dies a bit earlier as the degree of continuity goes down at the multiple knot points.