Background: In response to this recent question: $ E_8$ roots, OEIS entry A000712, and "Number of partitions of n into parts of 2 kinds" the MO contributor მამუკა ჯიბლაძე mentioned the Vinberg/Elashvili “trivector” $ E_8$ in 9-space as possibly relevant to my question: http://www.math.ucsd.edu/~nwallach/vin-elash.pdf Question: At an INTUITIVE and NAIVE level, is it correct toRead more