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A289718
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The order of the semigroup of orientation-preserving or reserving full transformations of n elements.
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1
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1, 4, 27, 180, 1015, 5028, 23051, 101272, 434835, 1843320, 7753471, 32440884, 135195307, 561615460, 2326740315, 9617256944, 39671268187, 163352387952, 671559953015, 2756930503420, 11303415274179, 46290177094172, 189368906605747, 773942488240920, 3160265160762575, 12893881856438128, 52567364492251191, 214163336821005012, 871950728486358835, 3547937446945462500
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OFFSET
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1,2
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LINKS
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FORMULA
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MAPLE
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n*binomial(2*n, n)-n^2*(n^2-2*n+5)/2+n ;
end proc:
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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