STS-41C was originally numbered STS-13. The crew played with the superstition idea and had this patch made for the crew (and wore it on their flight suits at times). Coincidentally, the shuttle landed on Friday the 13th:
VAN HOFTEN: Oh yes, triskaidekaphobia. In fact, you’ve probably seen the patch that Dick Scobee put together, the black cat patch. It was funny, because somewhere through our program NASA just decided they didn’t want thirteen anymore, and that’s when they invented all these goofy other labels, like we ended up 41-C that no one could ever figure out what that was. So we flew around with our STS-13 patch on, and that was a lot of fun. We ended up landing on Friday the 13th, so that was pretty cool. But no, it was really fun. - JSC Oral history
This is the Randy Hunt replica version.