The substitution rule is similar to Say-awen 17-fold. It is invariant under $21-$fold dihedral symmetry and has infinite local complexity. The substitution factor is $\mu_{21}=1/(2\sin(\pi/42))$, which is non-Pisot with minimal polynomial $p_{21}(x)=x^6-8x^5+8x^4+6x^3-6x^2-x+1$.