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A114572
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Number of "ultrasweet" Boolean functions of n variables which depend on all the variables.
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4
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OFFSET
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0,1
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COMMENTS
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Inverse binomial transform of A114491.
This sequence enumerates a certain type of matroid, except for the first entry (which is 2 instead of 1). If the first entry is changed from 2 to 1, giving A118085, this enumerates "combinatorial geometries" on n labeled points.
These are matroids in which no element has rank 0; equivalently, all one-element sets are independent; equivalently, the closure of the empty set is empty.
These are called "simple matroids" in A002773. So A118085 is the "labeled" equivalent of that sequence, which counts unlabeled points.
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LINKS
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EXAMPLE
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For all n>1, a function like "x2" is counted in A114491 but not in the present sequence.
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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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