mobius: function [n][
if n=0 -> return ""
if n=1 -> return 1
f: factors.prime n
if f <> unique f -> return 0
if? odd? size f -> return neg 1
else -> return 1
]
loop split.every:20 map 0..199 => mobius 'a ->
print map a => [pad to :string & 3]