I solved it.
*SPOILER ALERT* FOR THOSE WHO WISH TO TAKE A CRACK AT IT.
I broke the equation down to the factors that made sense and worked out the patterns from there. In Excel if A2 contained the DevID the serial number would equal
Code:
*****SPOILER ALERT******
=((10000+(RIGHT(A2,1)+3)+((LEFT(RIGHT(A2,2),1)+7)*10)+((LEFT(RIGHT(A2,3),1)-3)*100))*857)+660
A complex problem broken down into patterns of numbers based on an input / output table of 10 original pairs. I'm feeling pretty darn good right now!