Aren't Oracle's license fees based on the number of cores/threads available to the machine it's running on? (Or have they changed to number of sockets instead?)

Aren't Oracle's license fees based on the number of cores/threads available to the machine it's running on? (Or have they changed to number of sockets instead?) Seems like the most efficient way is to use a fewer number of powerful cores (as opposed to more not-as-powerful cores), but Oracle's customer base have more than enough money to spare, but so little brains that they use Oracle in the first place.