Quote Originally Posted by pando
Oracle changed licensing for Dual Core, you multiply by 1.5 CPU instead of 2
True, however you have to round the decimal result to the nearest upper integer. So, for a single dual core processor you must have two processor licenses (1*1.5=1.5 => roundet to 2), while for two dual core processors you have to pay three processor licenses (2*1.5=3).

Processors with hyperthreading are considered as a single core processors.