What is the electron configuration for thallium $($TI$)?$

Type it like this, with one space between each shell:

$1s22s22p63s2$dots

If you want to use the short way, please leave one space between each part again, like this:

$[Ar]4s23d10$dots

$1$s$22$s$22$p$63$s$23$p$63$d$104$s$24$p$64$d$105$s$25$p$64$f$145$d$106$s$26$p$1$