π - 2 = 1/1 + 1/3 - 1/6 - 1/10 + 1/15 + 1/21 - 1/28 ••• That's beautiful. I wonder why the -2 is there, though. To fix it, we would need π = -x + 1/1 + 1/3 -

π - 2 = 1/1 + 1/3 - 1/6 - 1/10 + 1/15 + 1/21 - 1/28 ••• That's beautiful. I wonder why the -2 is there, though. To fix it, we would need π = -x + 1/1 + 1/3 - 1/6 - 1/10 + 1/15 + 1/21 - 1/28 ••• where x = 2, and so it would be π = -1/½ + 1/1 + 1/3 - 1/6 - 1/10 + 1/15 + 1/21 - 1/28 ••• which makes the -1st triangle number ½, I guess.