Lah number
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![PDF] A new combinatorial interpretation of a $q$-analogue of the ...](/imgres?imgurl=https://d3i71xaburhd42.cloudfront.net/14e6a53d179c9b254ff7844d235938195942028b/10-Table1-1.png&imgrefurl=https://www.semanticscholar.org/paper/A-new-combinatorial-interpretation-of-a-of-the-Lah-Lindsay-Mansour/14e6a53d179c9b254ff7844d235938195942028b&h=370&w=1000&tbnid=7ah0ShvQJ-ak1M&q=Lah+number&tbnh=55&tbnw=149&usg=AI4_-kQBpnbDwAVOa_HtMKmoK_dgc-w_8Q&vet=1&docid=C2Yz6fYeBCLLsM&sa=X&ved=2ahUKEwjGw9ik9_yFAxVaVvEDHf4FAHoQ9QF6BAgAEAU)
![PDF] A new combinatorial interpretation of a $q$-analogue of the ...](/imgres?imgurl=https://d3i71xaburhd42.cloudfront.net/14e6a53d179c9b254ff7844d235938195942028b/17-Figure1-1.png&imgrefurl=https://www.semanticscholar.org/paper/A-new-combinatorial-interpretation-of-a-of-the-Lah-Lindsay-Mansour/14e6a53d179c9b254ff7844d235938195942028b&h=256&w=548&tbnid=ziTKF7TApLUVRM&q=Lah+number&tbnh=62&tbnw=133&usg=AI4_-kTFPy0ZIq-S_6BCSh0mWyaxp6w-dA&vet=1&docid=C2Yz6fYeBCLLsM&sa=X&ved=2ahUKEwjGw9ik9_yFAxVaVvEDHf4FAHoQ9QF6BAgAEAc)
In mathematics, the 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 are given by the formula involving the... Wikipedia