13 days is nothing to be concerned about for an adult corn but won't result in the snake becoming 'bony'. Seems you made the same error of months for days on a couple other posts as well.
If it is 13 days it may simply be that it is during breeding season and males especially will go off feed. One of my young females refused food for 2 months and has just taken a mouse again in the past week, so it could be nothing to be concerned about. It is also possible that your snake is just coming into a shed, and depending on the color of the snake it can be hard to detect.
I would continue to offer on a weekly basis, although if there is weight loss at this point, the failure to feed may be the end stage of an underlying problem. Bony body condition is enough to justify a trip to the vet in my books,