Assertion: triangle's number | /r/HasProperty | added
Facets:
Source sentences:
text: For example, the initial number in the first (or any other) row is 1 (the sum of 0 and 1), whereas the numbers 1 and 3 in the third row are added to produce the number 4 in the fourth row.
text: Again, the last number of a row represents the number of new vertices to be added to generate the next higher n-cube.