[Xe] 4f¹⁴ 5d¹ 6s²

Here's how it works:

* [Xe] represents the electron configuration of the noble gas Xenon (Xe), which is the element preceding Lutetium on the periodic table. This accounts for the first 54 electrons of Lutetium.

* 4f¹⁴ represents the 14 electrons in the 4f subshell.

* 5d¹ represents the single electron in the 5d subshell.

* 6s² represents the two electrons in the 6s subshell.

This abbreviated configuration is a shorthand way of expressing the full electron configuration of Lutetium, which would be: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹.