Number of primitive lattice triangulations of some rectangles


S. Yu. Orevkov

Last update: March 23, 2025

A lattice triangulation is a triangulation all whose vertices are at points with integer coordinates. It is primitive if each triangle is primitive, i.e. of area 1/2. Let f(m,n) be the number of primitive triangulations of an m x n rectangle. In the following files we give the exact values of these numbers for some m,n. The file named mxnf.txt contains a list

{f(m,1), f(m,2), ..... , f(m,n)}

3x600f.txt
4x200f.txt
5x115f.txt
6x70f.txt
7x34f.txt
8x20f.txt
9x12f.txt
10x10f.txt


The C-program for computing f(6,n) mod p, n=1,...,70: tr6x70.c


version 1 (Jan 30, 2022)
version 2 (Jul   06, 2024) 6x50f.txt is replaced by 6x57f.txt
version 3 (Aug   15, 2024) 8x13f.txt is replaced by 8x16f.txt
version 4 (Sep   01, 2024) 7x20f.txt is replaced by 7x28f.txt
version 5 (Sep   12, 2024) 9x9f.txt is replaced by 9x12f.txt
version 6 (Sep   29, 2024) 8x16f.txt is replaced by 8x20f.txt
version 7 (Oct   10, 2024) 10x10f.txt is added
version 8 (Jan   13, 2025) 7x28f.txt is replaced by 7x34f.txt
version 9 (Mar   23, 2025) 6x57f.txt is replaced by 6x70f.txt