Q:

Short symmetric formula for 'at most one of P, Q, and R is true'?

Just now I discovered that
$$
\text{at most one of } P, Q, R \text{ is true}
$$
is equivalent to
$$
((P \equiv Q) \land (Q \not\equiv R)) \:\:\equiv\:\: R
$$
I like this, but I don't like the loss of symmetry.  Is there perhaps another fairly short, but more symmetric, equivalent formula?
(As inspiration, note that
$$
\text{exactly one of } P,Q,R \text{ is true}
$$
is equivalent to
$$
(P \equiv Q \equiv R) \;\land\; \lnot(P \land Q \land R)
$$
which is nicely symmetric, since both $\;\equiv\;$ and $\;\land\;$ are symmetric and associative.)

A:

$$
\lnot[(P\land Q)\lor(Q\land R)\lor(R\land P)]
$$
$$
(\lnot P\lor\lnot Q)\land(\lnot Q\lor\lnot R)\land(\lnot R\lor\lnot P)
$$

