I'm definitely sure this has already been discovered by some mathematician way back, but I just discovered it today. Here it is: 1+2+3=6 3+4+5=12 5+6+7=18 7+8+9=24 Etc. What is this called (if it's called anything), and how does it work? And I'm mystified as to how the first numbers in each equation are odd (1, 3, 5, 7), and then there are even numbers (2, 4, 6, 8), and then there are odd numbers (3, 5, 7, 9), and then there are even numbers again (6, 12, 18, 24). Maybe I just inadvertently set it up that way? Thanks!