The 4017-decade counter can drive LEDs to form a chaser or sequencer type circuit. Here is a simple warning light application where the circuit flashes four LEDs one after another continuously. In this application, we use outputs Q0, Q1, Q2, and Q3 to drive the four LEDs, and output Q4 to reset the counter. By making the 4017 reset itself, it will flash the LEDs in a continuous manner.