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A294823
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Number of permutations of [n] avoiding {1234, 1324, 2341}.
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0
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1, 1, 2, 6, 21, 77, 284, 1041, 3789, 13730, 49679, 179906, 653083, 2378702, 8696754, 31921462, 117624497, 435047541, 1614769933, 6013417811, 22463101851, 84151166305, 316084324517, 1190187380109, 4491810419947, 16988382790291, 64379012014331, 244422429188511, 929587527276463
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OFFSET
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0,3
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LINKS
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MAPLE
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C := (1-sqrt(1-4*x))/2/x ;
((1 -4*x +5*x^2 -3*x^3)*C -(1 -4*x +6*x^2 -4*x^3))/(x*(1 -x)^2*(1 -2*x)) ;
taylor(%, x=0, 40) ;
gfun[seriestolist](%) ;
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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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