Let $T$ be a propositional theory over three variables $\{P, Q, R\}$ defined by the single axiom $T = \{P \implies (Q \land R)\}$. The Lindenbaum-Tarski algebra of $T$ is the Boolean algebra of all formulas modulo equivalence under $T$ (where $A \equiv_T B$ iff $T \vdash A \iff B$). How many elements are in the Lindenbaum-Tarski algebra of this theory?