Wow, didn't even remember posting this one. It's from before I started using microcontrollers, did it with an 8 pin AVR for under $1.00 ... I've got several boxes of 74xx and 40xx chips, that likely will never get used, but who knows. Most were pulled from sockets, and should be good.
Anyway, kind of like seeing people pull up old threads, better than the same questions being asked over and over. With all the flame-less candles on the market, surprised that there aren't LEDs with built in flicker circuits. They blink, they fade RGB, why not flicker?