Order 20: Marshall Hall Class 01 (this is as yet unchecked it comes from the Paley matrix of order 20) ---------01 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 - - - - - - - - - - 1 1 1 1 1 - - - - - 1 1 1 1 1 - - - - - 1 1 1 1 - 1 - - - - 1 - - - - 1 1 1 1 - 1 1 1 - - - 1 1 - - - 1 1 - - 1 1 - - 1 1 1 - 1 - - 1 - 1 - - - - 1 1 1 - 1 - 1 1 1 - - 1 1 - - - 1 - 1 - 1 - 1 - - 1 1 1 1 - - 1 - - - 1 1 1 - 1 - - - 1 1 - 1 1 1 - - - 1 - 1 1 - - 1 1 - 1 - - 1 1 - 1 1 - - - - 1 1 - 1 1 - - 1 1 - 1 - 1 - 1 - 1 1 - - - 1 - 1 - - 1 1 - - - 1 1 1 1 - 1 - 1 - 1 - 1 - - 1 - 1 - - 1 1 1 - 1 - 1 - 1 - - 1 1 - 1 - - - 1 1 - - 1 1 1 - 1 - - 1 1 - - 1 1 1 - - 1 - - 1 - 1 1 - 1 - - 1 - - 1 1 - - 1 1 1 1 1 - - - 1 - - 1 1 1 1 - - - - - 1 - 1 - 1 - 1 1 1 - - 1 1 - - 1 - 1 - 1 - - 1 1 1 1 - - 1 - - 1 - 1 - 1 1 - 1 1 - 1 - - 1 - - 1 1 - - 1 - - 1 - 1 1 1 1 1 - - 1 - - 1 - 1 - - - 1 1 1 1 - - 1 - 1 1 - 1 - 1 - - or 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1-1 1-1-1 1 1 1 1-1 1-1 1-1-1-1-1 1 1-1 1-1-1 1-1-1 1 1 1 1-1 1-1 1-1-1-1-1 1 1 1 1-1-1 1-1-1 1 1 1 1-1 1-1 1-1-1-1-1 1 1 1 1-1-1 1-1-1 1 1 1 1-1 1-1 1-1-1-1-1 1-1 1 1-1-1 1-1-1 1 1 1 1-1 1-1 1-1-1-1 1-1-1 1 1-1-1 1-1-1 1 1 1 1-1 1-1 1-1-1 1-1-1-1 1 1-1-1 1-1-1 1 1 1 1-1 1-1 1-1 1-1-1-1-1 1 1-1-1 1-1-1 1 1 1 1-1 1-1 1 1 1-1-1-1-1 1 1-1-1 1-1-1 1 1 1 1-1 1-1 1-1 1-1-1-1-1 1 1-1-1 1-1-1 1 1 1 1-1 1 1 1-1 1-1-1-1-1 1 1-1-1 1-1-1 1 1 1 1-1 1-1 1-1 1-1-1-1-1 1 1-1-1 1-1-1 1 1 1 1 1 1-1 1-1 1-1-1-1-1 1 1-1-1 1-1-1 1 1 1 1 1 1-1 1-1 1-1-1-1-1 1 1-1-1 1-1-1 1 1 1 1 1 1-1 1-1 1-1-1-1-1 1 1-1-1 1-1-1 1 1 1 1 1 1-1 1-1 1-1-1-1-1 1 1-1-1 1-1-1 1-1 1 1 1 1-1 1-1 1-1-1-1-1 1 1-1-1 1-1 1-1-1 1 1 1 1-1 1-1 1-1-1-1-1 1 1-1-1 1 1 1-1-1 1 1 1 1-1 1-1 1-1-1-1-1 1 1-1-1 SNF: 1,2^9,10^{9},20 Quadratic Residues: 1 4 5 6 7 9 11 16 17