Talk:2018 AIME II Problems/Problem 15

The provided solution appears to be incorrect. It does not appear to take into account the possibility that e.g., $d_k$ is -2 or -3.

I believe the correct answer is 267. There is a relatively simple dynamic programming solution for this (which I'm happy to provide), but we can also confirm with the following Python script:

deltas = [-3,-2,-1,1,2,3]
count = 0
for d1 in deltas:
  for d2 in deltas:
    for d3 in deltas:
      for d4 in deltas:
        for d5 in deltas:
          for d6 in deltas:
            if d1 + d2 + d3 + d4 + d5 + d6 == 12:
              count += 1
print count