Single output to sequence LED
Your circuit is poor because the further up the chain you go the more voltage drop will occur on the first few LEDs. Also where are your LED current limiting resistors?

Instead, since the LEDs are controlled by a micro-controller you "multiplex" them. This means scanning all 16 LEDs faster than the eye can see - maybe 50 times a second - and turning each one on as required for a short high-current pulse.







simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. To light the first four LEDs the strobe sequence would be as shown.

Check the datasheet for your LEDs and there should be a peak current rating typically giving the maximum pulse current, duration and duty cycle.