Springwolf, I've never heard that, and in fact, the fear of the number 13 and Fridays are a worldwide phenomenon, not just in Christian countries. The Turkish people especially, loathe the number 13.
Besides, you're quoting the legend incorrectly. The King of France and the Pope were supposed to be at odds with each other, and the Pope had excommunicated the King. Which is why the King put out an order to jail and then kill the Knights of the Templar.
There are differing opinions concerning the legend, nor has there ever been corroborating evidence for or against it.
I consider the number 13 to be lucky, because it's the number of Christ and the disciples. Plus, who doesn't love Friday?