1 may be the saddest number but what about 13? - Brian Sullivan

I wonder why 14 is also missing from that elevator; and why in the world does it start with -1? ETA - Just noticed it's missing 4, too. That's weird - COMPLICATED MR. NOODLE

"An elevator in a residential apartment building in Shanghai. Floor numbers 4, 13 and 14 are missing, and there is a button for the "negative first floor"." - Brian Sullivan

"Tetraphobia, fear of the number 4. In Korea, China and Japan, as well as in many other East-Asian and some Southeast-Asian countries, it is not uncommon for buildings (including offices, apartments, hotels) to lack floors with numbers that include the digit 4" - Brian Sullivan