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A305554
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Sum of the areas of all D-elevated skew paths of semi-length n.
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0
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0, 1, 4, 22, 116, 600, 3072, 15634, 79256, 400718, 2022160, 10189974, 51292608, 257965512, 1296483996, 6512176890, 32694946020, 164082802440, 823188507360, 4128668625430, 20701989426800, 103781348220380, 520167491584660, 2606714240022090, 13061050758478620, 65434115386531850
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OFFSET
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0,3
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LINKS
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Emeric Deutsch, Emanuele Munarini, Simone Rinaldi, Skew Dyck paths, area, and superdiagonal bargraphs, Journal of Statistical Planning and Inference, Vol. 140, Issue 6, June 2010, pp. 1550-1562.
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FORMULA
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G.f.: x*(2-4*x-sqrt(1-6*x+5*x^2))/(1-5*x).
D-finite with recurrence: (-n+1)*a(n) +(11*n-20)*a(n-1) +5*(-7*n+19)*a(n-2) +25*(n-4)*a(n-3)=0.
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MAPLE
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g := x*(2-4*x-sqrt(1-6*x+5*x^2))/(1-5*x) ;
taylor(g, 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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