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A305554
Sum of the areas of all D-elevated skew paths of semi-length n.
0
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
OFFSET
0,3
LINKS
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.
FORMULA
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.
MAPLE
g := x*(2-4*x-sqrt(1-6*x+5*x^2))/(1-5*x) ;
taylor(g, x=0, 40) ;
gfun[seriestolist](%) ;
CROSSREFS
Sequence in context: A272435 A106835 A293966 * A291183 A374454 A245087
KEYWORD
nonn,easy
AUTHOR
R. J. Mathar, Jun 21 2018
STATUS
approved