OFFSET
1,2
LINKS
Jean-Luc Baril, Pamela E. Harris, and José L. Ramírez, Flattened Catalan Words, arXiv:2405.05357 [math.CO], 2024. See p. 10.
Index entries for linear recurrences with constant coefficients, signature (8,-22,24,-9).
FORMULA
From Baril et al.: (Start)
G.f.: x*(1 - 2*x)^3/(1 - 4*x + 3*x^2)^2.
a(n) = (27 - 9*n + (5 + n)*3^n)/36. (End)
E.g.f.: (exp(3*x)*(5 + 3*x) - 9*exp(x)*(x - 3) - 32)/36.
MATHEMATICA
LinearRecurrence[{8, -22, 24, -9}, {1, 2, 6, 20}, 29]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Stefano Spezia, May 15 2024
STATUS
approved