Triangle numbers 9 digit repeating sequence

I have worked with the triangle numbers a lot but one thing I have never done is look at its repeating sequence but thanks to @sphere_baba_afrospheer (Instagram), who messaged me about it, I decided to take a look at it and it has some very interesting patterns and an interesting link to the sum of all numbers being -1/12 which may be a vortex based math proof for the sum of all numbers.