[nsp] regexp question

[Peter L]

Hi
I have a question regarding a regular expression I'm trying to fix and
hopefully someone that's excellent at regular expressions can help me. I
would like to accept everything from a peer + everyting from the ASs his
peering with directly. Example:
Accept:
1234 1234
1234 567
1234 1234 655
1234 654 654
Deny:
1234 654 989
or
1234 567 567 2323
ando so forth..
So far I have:
^(1234_)+([0-9]+)*$
This accepts everthing except when the second AS is prepended(1234 654 654).
Is i possible to fix this in one expression? Otherwise I have to setup
filters for every AS and that would not be very dynamic.

Thank you
Peter