Start with 1. Use 1 as a multiplier of the previous term for the next 1 term. 1x1 = 1 Use 2 as a multiplier of the previous term for the next 2 terms. 1x2 = 2 2x2 = 4 Use 3 as a multiplier of the previous term for the next 3 terms. 4x3 = 12 12x3 = 36 <-- (that's the answer, but let's keep going a little more.) 36x3 = 108 Use 4 as a multiplier of the previous term for the next 4 terms. 108x4 = 432 432x4 = 1728 1728x4 = 6912 6912x4 = 27648 Edwin