The pattern in the series is based on the cubes of consecutive integers multiplied by the integer itself. The sequence can be represented as n * (n+1)^2. For n=1, 1*(1+1)^2 = 1*4 = 4 (there seems to be a discrepancy with the first term provided in the question, assuming the sequence logic starts from n=1 for the second term). For n=2, 2*(2+1)^2 = 2*9 = 18 (also not matching). Let's re-evaluate. Another common pattern is n^3 + n or n^3 - n or similar. Let's check differences. 12-2=10, 36-12=24, 80-36=44, 150-80=70. Second differences: 24-10=14, 44-24=20, 70-44=26. Third differences: 20-14=6, 26-20=6. This indicates a cubic relationship. The general term is likely of the form An^3 + Bn^2 + Cn + D. Given the third difference is constant (6), the coefficient of n^3 is 6/6 = 1. Let's test the sequence n(n+1)(n+2). For n=1: 1*2*3 = 6. Not matching. Let's try n^2*(n+1). For n=1: 1^2*(1+1) = 2. For n=2: 2^2*(2+1) = 4*3 = 12. For n=3: 3^2*(3+1) = 9*4 = 36. For n=4: 4^2*(4+1) = 16*5 = 80. For n=5: 5^2*(5+1) = 25*6 = 150. This pattern fits. Therefore, for n=6, X = 6^2*(6+1) = 36*7 = 252.