I'm writing something up and I'm just wondering if there's a notation and/or name for the function which maps the elements of a sequence $(a_1, a_2, \dots)$ (or the finite sequence $(a_1, \dots, a_n)$) to the set which contains all of the same elements $\{a_1, a_2, \dots\}$.
I'm fine with just making up a notation, but I feel like this might be something someone has already come up with a standard symbol for, though a quick Google search didn't find me one.