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A324063
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Number of defective (binary) heaps on n elements where two ancestor-successor pairs do not have the correct order.
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2
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0, 0, 0, 2, 6, 24, 100, 480, 1890, 8960, 47040, 288000, 1584000, 10644480, 74131200, 615014400, 3783780000, 29520691200, 230015385600, 2199674880000, 17239951872000, 172890685440000, 1660143513600000, 19778694414336000, 174145223476224000, 2007117934991769600
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OFFSET
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0,4
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COMMENTS
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Or number of permutations p of [n] having exactly two pairs (i,j) in {1,...,n} X {1,...,floor(log_2(i))} such that p(i) > p(floor(i/2^j)).
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LINKS
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Eric Weisstein's World of Mathematics, Heap
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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