WORKING:
The pins 2 and 6 are connected together allowing the circuits to re trigger itself on each and every cycle and thus allows it to operate as a free running oscillator. During each cycle capacitor charges up through both timing resistors but discharges itself only through the resistor in which other side is connected to the discharge terminal pin 7.
The capacitor charges up to 2/3 Vcc ( the upper capacitive limit) which is determined by 0.693*(R1+R2)*C and discharges itself down to Vcc/3 (the lower capacitance limit) determined by 0.693*R2*C. This results in an output waveform whose voltages is approx equal to Vcc-1.5 V and whose output ON and OFF time periods determined by the capacitor resistor combinations.
