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
KEYWORD
nonn,easy
AUTHOR
R. J. Mathar, Jun 21 2018
STATUS
approved