How can I type double struck 1, i.e. indicator function in eq?
I tried to search for this the whole morning but failed. Things I tried:
\mathbb{1}, \mathbbm{1}, \cmathbb{1}. \mmathbb{1}, \Bbb{1}, \char"1D7D9 (this should be the correct UNICODE, but it only outputs a mysterious character).
Thanks!