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  "body": "\n## Summary\n\nIn mathematics, the (**signed and unsigned**) **Lah numbers** are coefficients expressing rising factorials in terms of falling factorials and vice versa. They were discovered by Ivo Lah in 1954. Explicitly, the unsigned Lah numbers $L(n, k)$ are given by the formula involving the [[binomial coefficient|092GEF38YD]]\n",
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