Levered Free Cash Flow Formula

I'm trying to understand how Seeking Alpha calculates the Levered Free Cash Flow (LFCF) values that it displays on the Free Cash Flow page under Financials.  When I Google how LFCF should be calculated, I see differing methodologies from a few sources. However when I apply all of the different calculations that I have found using the data that Seeking Alpha presents for a company, none of these various methodologies are producing the same LFCF result that Seeking Alpha presents (and what I am coming up with is not even close to Seeking Alpha).  

Is it possible to receive the formula that Seeking Alpha uses, or is this proprietary information?  

Hopefully I can receive it so that I can verify and trust the LFCF numbers provided by Seeking Alpha.