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ΣΣΣΣΣΣ — exactly 3 charactersCombinedFormal RE✨ Emoji Combos

Three Σ concatenated accepts exactly strings of length 3. L(ΣΣΣ) = Σ³. Generalizes to Σⁿ for any fixed n.

✓ Accepts
abc123a bxyz
✗ Rejects
εababcda
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