Yes, although it may be more convenient to buy it with the iPad.
See the following from AppleCare Products - iPad - Apple
How to buy
- Purchase AppleCare+ with your new iPad.
- Or buy it within 60 days of your iPad purchase:
- On your device (go to Settings > General > About and choose AppleCare+ Coverage Available)
- Online (requires you to verify your serial number and run a remote diagnostic)
- At an Apple Store (inspection of iPad and proof of purchase are required)
- By calling 800-275-2273 (requires you to run a remote diagnostic and provide proof of purchase)