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A275801
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Number of alternating permutations of the multiset {1,1,2,2,...,n,n}.
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4
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1, 0, 1, 4, 53, 936, 25325, 933980, 45504649, 2824517520, 217690037497, 20394614883316, 2282650939846781, 300814135522967736, 46103574973075123877, 8130996533576437261772, 1635028654501420083152785, 371853339350614571322913824, 94969025880924845123887493233
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OFFSET
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0,4
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COMMENTS
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Number of permutations (p(1),...,p(2n)) of {1,1,2,2,...,n,n} satisfying p(1) < p(2) > p(3) < ... < p(2n).
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LINKS
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CROSSREFS
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Cf. A000111, A001250, A000459, A004075, A005799, A114938, A137729, A137730, A137737, A137749, A275829.
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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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