Equiatomic configurational entropy ($\Delta S_{\mathrm{mix}}=R\ln n$)

Randomly distributing $n$ species with equal fractions over $N$ sites gives $\Omega =N!/[(N/n)!{]}^n$. Stirling approximation gives $S=k_{B}N\ln n$, or $R\ln n$ per mole of sites. Configurational entropy alone does not decide whether a multicomponent alloy is a stable single thermodynamic phase.