[**white paper: pedagogical**]

We show using induction on complexity that all terms of a language with one constant, one binary function, and one 4-ary function have an odd number of symbols.

https://doi.org/10.31219/osf.io/ue32a

**Open Mathematics Collaboration**

Op. J. Math. Phys.

Volume 3, Article 231, 2021 [JB]