Friday the 13th to Occur 3 Times, 13 Weeks Apart", tells us all we need to know. A pagan bookstore owner warns in article, "'...[who] calls the fears a 'self-fulfilling prophecy.' There is 'strong power in people convincing themselves something unlucky will happen,' he says." It can be self-fulfilling, but there are also those who live by the numbers!
Occultists consider the number 13 divine for a couple of reasons, according to a Bibliotecapleyades.net entry, "1. The Bible assigns '13' the meaning of 'rebellion against constituted authority', plus the depravity that caused Satan to rebel against God. 2. The occultist assigns '6' to represent the number of man, and the number '7' to represent the number of divine perfection. Thus, as a person climbs that "Jacob's Ladder" toward self-perfection in the realm of the occult, the number '13' represents the state of divine perfection, self-achieved perfection, and Illumination (6+7 = 13)." It's one more concern for the apocalyptic year of 2012!