As per i understand you well, the regex pattern should look like:
^(9838|9839|9918|9919)\d{6}\-\w{6}$*
with mulitline option set to true.
I tested it on:
9839337719-XXYYAB
9839733119-AXXYYZ
9839912300-AXYZ00
9838488886-AUXXXU
9839522238-AXXXYZ
9839295588-ABXXYY
9949488886-AUXXXY
9839257772-AXYYYZ
9839488886-AXXXXY
9859488886-AXXXXY
It returns 8 records fulfilling criteria (the last one is ignored).