bn2.py

base = []
for i in range(7):
    base.append((-2)**i)
base = base[::-1]
values = []
valueDict = {}

for x in range(2):
    for x1 in range(2):
        for x2 in range(2):
            for x3 in range(2):
                for x4 in range(2):
                    for x5 in range(2):
                        for x6 in range(2):
                            tup = (x,x1,x2,x3,x4,x5,x6)
                            val = base[0]*x + base[1]*x1 + base[2]*x2 +base[3]*x3 + base[4]*x4 + base[5]*x5 + base[6]*x6
                            values.append(val)
                            valueDict[val] = tup

print sorted(set(values))

for key in sorted(valueDict.iterkeys()):
    print "%3s: %s" % (key, valueDict[key])

        

so extensible