One solution is f(x) = x/2 - x/5 - x/9 - 2(x/17) - x/33 - x/65 - x/129 - 4(x/257) - x/1025 - x/2049 - 2(x/4097) - x/8193 - x/32767 - 8(x/65537) - x/131073 - x/524289 - 2(x/1048577) + x/2097153 - x/4194305 - x/8388609 - 4(x/16777217) - x/67108865 - x/268435457 - x/1073741825 Andrew