Hello VQC! I knew you'd be popping in. Here's some work in progress.
For c287
e prime | (31,8,5) = {31:8:16:9:7:41} = 287; f=2; (f%8)=2; (x+n)=17; u=8; (d+n)=24
e na | (31,1,8) = {31:1:143:15:128:160} = 20480; f=256; (f%8)=0; (x+n)=16; u=8; (d+n)=144
na a value = 128
128 div 16 (prime d value) = 8 = n