# How to find lattice coefficients when k2=1?

$$H(z)=1+2z^{-1}+z^{-2}$$

We know the formula

$$a_{m-1}\;(k)=\frac{a_m\;(k)-k_m\;a_m\;(m-k)}{1-k_m\;^2}$$

Here $$k_2=1$$ That makes $$a_{m-1}\;(k)=infinity$$

How to find lattice coefficients of all pole IIR filter with filter coefficient $k_m$ is 1?

I have read this answer but it is not similar to this question