import itertools as it
import numpy

count = 0
valid = 0
for points in it.combinations(it.product(range(4), repeat=2), 3):
    count = count + 1
    for a, b, c in it.permutations(points):        
        ab = numpy.subtract(b, a)
        ac = numpy.subtract(c, a)
        if numpy.dot(ab, ac) == 0:
            valid = valid + 1
            print("%3d: %s" % (valid, points))
            break;
print("\np=%d/%d" % (valid, count))