http://lostpedia.wikia.com/wiki/Valenzetti_Equation

The Valenzetti Equation is the mathematical equation developed by the reclusive Princeton University mathematician Enzo Valenzetti. Its creation was the result of efforts made following the Cuban Missile Crisis by the United States and the Soviet Union to find a solution to the hostility and danger of imminent global disaster created by the Cold War. The equation was secretly commissioned through the UN Security Council and is used to predict the time of human extinction.

The Valenzetti Equation "predicts the exact number of years and months until humanity extinguishes itself."

The numbers, 4, 8, 15, 16, 23 and 42, are explained as the numerical values to the core environmental and Human Factors of the Valenzetti Equation