Pairing a Logitech K760 bluetooth keyboard using the GNOME 3.14 interface does not work. It is necessary to use a workaround that requires use of hcidump to manually display the passkey.

An Apple Bluetooth keyboard pairs just fine, and the GNOME UI presents the passkey to enter on the keyboard.

The hcidump workaround is listed here:

http://askubuntu.com/questions/290330/logitech-k760-failing-to-pair-ubuntu-13-04