[ false swap
    behead swap
      [ witheach
          [ tuck != if
              done
            dip not
            conclude ] ]
    drop ]               is square ( [ --> b )

  [ 1 & ]                is odd    ( n --> b )

  [ dup 1 = if done
    primefactors
    dup square iff
      [ drop 0 ] done
    size odd iff
      -1 else 1 ]        is mobius ( n --> n )

  say "First 199 terms:" cr
  say "    "
  199 times
    [ i^ 1+ mobius
      dup -1 > if sp
      echo
      i^ 1+ 20 mod
      19 = iff cr
      else [ sp sp ] ]