The rule of 0 1 3 6 10 15 21 28 36 (expressed by n),,,,, you prawns are bubbling ,,,,,, n denote

The rule of 0 1 3 6 10 15 21 28 36 (expressed by n),,,,, you prawns are bubbling ,,,,,, n denote

This rule is not very difficult, we can see that the difference between each number is gradually increasing, for example, the difference between 0 and 1 is 1, the difference between 1 and 3 is 2, the difference between 3 and 6 is 3, the difference between 6 and 10 is 4, and so on
This is actually a summation problem of arithmetic sequence, the first term A1 = 0, arithmetic is 1, so the general term is n (n-1) / 2
Hope it answers your question