Northern Indiana Public Service Company
From The RadioReference Wiki
It appears the LCN's for the entire system are based on the following equation:
LCN = (FREQ - 934.9875) / 0.0125
This calculation has been confirmed to work correctly on the Oakdale Dam, Chase and Monticello sites. It also lines up with several other sites and their confirmed LCN's listed in the database.
JUST A REMINDER- as has been mentioned in several of the forums, there are some discrepancies between what the FCC database lists as licensed frequencies and what are actually used at each site.