There are $\binom{n+2}{4}$ equilateral triangles in the regular $n$-vertices-per-side triangular grid, by choosing four-elements subset $\{A,B,C,D\}$ of$A<B<C<D$ from the set $\{1,...,n+2\}$: https://arxiv.org/abs/2211.00186
There are $\binom{n+2}{4}$ equilateral triangles in the regular $n$-vertices-per-side triangular grid, by choosing four-elements subset $\{A,B,C,D\}$ of the set $\{1,...,n+2\}$: https://arxiv.org/abs/2211.00186
There are $\binom{n+2}{4}$ equilateral triangles in the regular $n$-vertices-per-side triangular grid, by choosing $A<B<C<D$ from the set $\{1,...,n+2\}$: https://arxiv.org/abs/2211.00186
There are $\binom{n+2}{4}$ equilateral triangles in the regular $n$-vertices-per-side triangular grid, by choosing four-elements subset $\{A,B,C,D\}$ of the set $\{1,...,n+2\}$: https://arxiv.org/abs/2211.00186