How does one go about creating a new mathematical symbol? Suppose I propose a new symbol, establish its need...and then all of you start using it. Perhaps the new symbol will spread and eventually be adopted universally!
We all know that 6*5*4*3*2*1 = 6!. But less know that the symbol "!" for factorial was a purposeful move suggested by a printer in 1808, working on a manuscript for Christian Kramp, a Strassbourg mathematician.
Similarly, we need a symbol for expressing 6+5+4+3+2+1. Like Kramp's printer, I have scoured the keyboard, looking for a symbol that has no other common use in mathematics (i.e. exactly why ! was the choice for factorial). And the result was using 6↵, 6⊕, or 6&.
But, 6& is too hard to write by hand. And 6⊕ is already used to mean vector addition. So, my proposed winner is 6+5+4+3+2+1 = 6↵, and we will call it "sumtorial."
Now go spread the word.....