We can point to no rules that specifically address Pascal's triangle.
If possible, it would be appropriate to follow print's triangular layout of a representation of Pascal's triangle. The content of the triangle determines which code (Nemeth or UEB) will be used.
Since we're talking about a transcription using Nemeth within UEB, in your sample of print, the triangle made up of C's with subscripts must be transcribed in Nemeth Code, and the triangle made up of whole unmodified numbers may be transcribed in Nemeth Code or in UEB.
Attached is a BRF with both triangles from your sample print transcribed, with the longest row (i.e., the base) of the triangle beginning in cell 1 and each smaller row centered relative to the row below it.
This reply was modified 3 years, 5 months ago by kdejute. Reason: full answer replaces "answer pending" response