I'm not sure about this, but I would say 1,1,2,6,6,12,36,36,72,216,216,432
2 is formed from the sum of the two before it. Every number in a place that is a multiple of 3 i.e. 2,12, and 72, is multiplied by three. That number is then repeated and the sum taken. It seems strange, but it works for what you have given.