Hi,
here is a circuit as suggested. The timer output frequency is 2Hz. D1 through D3 make a diode network to have the LED blink every second clock pulse. The counter then coninues to count 9 and resets from pin11 to pin15 (which is actually not required since the IC starts automatically at the count of zero after count 9)
You might want to use shorter breaks between three flashes. Use Q6(pin5), Q7(pin6) or Q8(pin9) connected to pin15 to achieve shorter breaks.
For a clock freqency of approximately 1Hz use 6.8MΩ for R2
Boncuk