X is to roll 4d6 six times, always discarding the lowest roll in a each group of die. According to the What the 4d6 - drop -low mechanic is is really 4k3, but with d6s instead of .. Check out the formula below in AnyDice! Stat-rolling math problem.
On the Paizo board, it was recently asked what the exact statistics are for the character generation method of 4d6 drop the lowest. That is, if you.
One method of generating those is by rolling 4d6 drop lowest. it's worth noting that anydice.com provides a calculator for precisely this.