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A065181
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Permutation of nonnegative integers produced when the finite permutations listed by A055089 are subjected to inverse of Foata's transformation. Inverse of A065182.
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8
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0, 1, 2, 5, 3, 4, 6, 7, 14, 23, 17, 20, 8, 11, 12, 22, 13, 21, 9, 10, 16, 18, 15, 19, 24, 25, 26, 29, 27, 28, 54, 55, 86, 119, 95, 110, 62, 71, 78, 116, 79, 113, 65, 68, 92, 102, 89, 103, 30, 31, 38, 47, 41, 44, 48, 49, 84, 118, 94, 108, 50, 53, 80, 117, 83, 109, 51, 52
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OFFSET
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0,3
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COMMENTS
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Here we use the inverse of the left-right maxima variant of Foata's transformation, which works by rotating each cycle largest element first and then sorts the cycles to ascending order, according to that first (and largest) element of each.
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REFERENCES
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I.M. Gessel and R. P. Stanley, Algebraic Enumeration, chapter 21 in Handbook of Combinatorics, Vol. 2, edited by R.L.Graham et al., The MIT Press, Mass, 1995, page 1045.
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LINKS
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MAPLE
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[seq(PermRevLexRank(FoataInv(PermRevLexUnrank(j))), j=0..119)];
with(group); FoataInv := p -> map(op, sort([op(map(RotCycleLargestFirst, convert(p, `disjcyc`))), op(FixedCycles(p))], sortbyfirst));
sortbyfirst := (a, b) -> `if`((a[1] < b[1]), true, false);
FindLargest := proc(a) local i, m; m := 0; for i from 1 to nops(a) do if(0 = m) then m := i; else if(a[i] > a[m]) then m := i; fi; fi; od; RETURN(m); end;
RotCycleLargestFirst := proc(c) local x; x := FindLargest(c); if(x <= 1) then RETURN(c); else RETURN([op(c[x..nops(c)]), op(c[1..(x-1)])]); fi; end;
FixedCycles := proc(p) local a, i; a := []; for i from 1 to nops(p) do if(p[i] = i) then a := [op(a), [i]]; fi; od; RETURN(a); end;
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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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