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A178008
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Number of permutations of 1..n with no element e[i>=2]<e[1+floor((i-2)/3)] (3-way heap).
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4
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1, 1, 1, 2, 6, 12, 40, 180, 630, 3360, 22680, 113400, 831600, 7484400, 38918880, 302702400, 2918916000, 20432412000, 205837632000, 2500927228800, 21598916976000, 263986763040000, 3837961401120000, 33774060329856000, 431557437548160000, 6658314750743040000
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OFFSET
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0,4
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LINKS
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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