How can I get the taps for feedback with PN sequences?

[Jessica]

pn23 taps

Dear all,

I do't know how to get the taps for feedback with PN sequence.
For Example, the PN4 feedback taps are [5,3] [5,2] and
the PN23 feedback taps are [23,18] [23,5].
How do I get [5,3] [5,2] and [23,18] [23,5]?

Thanks!