primes p = 1 mod 4, 5 <= p <= 10000000: 332180; all checked (det B = p, B positive definite).
record values of the least l = 3 mod 4 with (l/p) = -1  (p, l): [(5, 3), (13, 7), (37, 19), (709, 23), (1453, 31), (5413, 59), (30493, 67), (83077, 71), (141157, 79), (365509, 83), (432793, 103), (602317, 127), (880993, 131), (9665041, 139)]
distribution of l: {3: 166169, 7: 83051, 11: 41508, 19: 20901, 23: 10441, 31: 5135, 43: 2568, 47: 1268, 59: 612, 67: 281, 71: 130, 79: 71, 83: 25, 103: 8, 107: 4, 127: 5, 131: 2, 139: 1}
python3 least_l.py 10000000  0.71s user 0.01s system 99% cpu 0.724 total
