My outdoor cat has been missing for about 3.5 weeks now.?

Its very unusual as he never strays out of our yard. Every time I come home he greets me on the front porch. I have placed fliers on telephone poles, grocery stores, and other stores in the area, as well as placed fliers in my entire neighborhood's mailboxes. I also put fliers at all the local vets and the animal shelter. 3 people have claimed to have seen my cat in the same neighborhood about half a mile from my house. We set up a cat rescue trap in one person's yard and left it there for 3 days, but nothing. :( I'm looking for advice on what else I can do to try and get my kitty to come home. I have visited the area everyday where people have claimed to have seen him and have called him, shook his food in a can, and searched the woods for him..but nothing. I feel so helpless and I'm not sure if he's lost or if he doesn't want to be found. Any advice would be greatly appreciated