You see 2 equal IC circuits. They are linked with this 8uF Capacitor in between the IC's. Here there are two of them. The right one is the last one and connected from the output (3) over a switch to the trigger (2) of the first one. If the switch is open there is gonna be just one sequence. Closed it'll loop.
R 82k and C 22uF determine the frequency of the led's . You start the 555 sequencer with that tap switch at the 1st 555.
10 of them make a nice running light or a night rider with 5 Lamps. Over Opto coppler or relays you can steer higher loads.
Enjoy.
