I need a sanity check. Does this answer make sense?
https://math.stackexchange.com/a/553998/29335
It appears to be plagiarized from [this blog](https://mathtopics.wordpress.com/2012/01/03/ideals-in-the-ring-of-upper-triangular-matrices/) but anyhoo it doesn't seem to make sense to me. Note the $n_{ij}$ and the $d_{ij}$s.