A055582 Sixth column of triangle A055252.

1, 9, 48, 198, 699, 2223, 6562, 18324, 49029, 126837, 319332, 786258, 1900351, 4521771, 10616598, 24641280, 56622825, 128974545, 291503800, 654311070, 1459617411, 3238002279, 7147093578, 15703473708, 34359737869, 74893491693

Offset: 0

Author

Wolfdieter Lang, May 26 2000

Keywords

• easy
• nonn

Links

• Michael De Vlieger, Table of n, a(n) for n = 0..3296
• Robert Davis, Greg Simay, Further Combinatorics and Applications of Two-Toned Tilings, arXiv:2001.11089 [math.CO], 2020.
• Index entries for linear recurrences with constant coefficients, signature (9, -33, 63, -66, 36, -8).

Crossrefs

Cf. A055252, A055249, A034009, partial sums of A055581.

Programs

Mathematica

CoefficientList[Series[1/(((1 - 2 x)^3) (1 - x)^3), {x, 0, 25}], x] (* Michael De Vlieger, Apr 23 2020 *)

Formula

G.f.: 1/(((1-2*x)^3)*(1-x)^3).

a(n)= A055252(n+5, 5). a(n)= sum(a(j), j=0..n-1)+A034009(n), n >= 1.

a(n)= (n^2 - 3*n + 8)*(2^(n+3) -1)/2 - 9*(n+3). [Yahia Kahloune, Aug 11 2013]