OFFSET
3,2
LINKS
Jean-Luc Baril, Pamela E. Harris, and José L. Ramírez, Flattened Catalan Words, arXiv:2405.05357 [math.CO], 2024. See p. 22.
Index entries for linear recurrences with constant coefficients, signature (9,-30,46,-33,9).
FORMULA
From Baril et al.: (Start)
G.f.: (1 - 2*x)^2*x^3/((1 - 3*x)^2*(1 - x)^3).
a(n) = (63 + 3^n + 2*(3^n - 45)*n + 18*n^2)/144. (End)
E.g.f.: (exp(3*x)*(1 + 6*x) + 9*exp(x)*(7 - 8*x + 2*x^2) - 64)/144.
MATHEMATICA
LinearRecurrence[{9, -30, 46, -33, 9}, {1, 5, 19, 67, 230}, 28]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Stefano Spezia, May 15 2024
STATUS
approved