Here's a table showing you the letters for what you'll need. I'm not sure about the j, it might be a d you are looking for. j has no leading zeros, d has leading zeros.
2003-04-19 14:35:30
Y- d- j H: i: s
The table's format just lines everything up, and it's relevant to how it's printed out. Your actual date() call should look like this:
date("Y-d-j H:i:s");