Suppose I have a column of 10 numbers and I want to know what the average of the sums of each number with each other number (except itself) is. So it would be the average of the sum of, for example, A1+A2, A1+A3....,A8+A10,A9+A10.

What is the fastest way to do this? My current method of fixing one cell constant and iterating through every other cell seems incredibly tedious. The other, better method I found is to create a table cycling through each one with relative references. Is there a way to do this in one cell though?