A polyiamond is an edge-connected set of cells on the triangular lattice. If T(n) denotes the number of distinct (up to translation) polyiamonds made of n cells. It is known that the limit λT of T(n+1)/T(n) (the growth constant) exists. In this paper, we improve the best upper bound on λT from 4 to 3.6108.
The proof relies on a computer calculation, which was done in the Sage system with a simple script.
Last update: September 30, 2019.