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A055582 Sixth column of triangle A055252. 7
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

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.

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]

MATHEMATICA

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

CROSSREFS

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

Sequence in context: A212107 A073979 A018984 * A054460 A115053 A181959

Adjacent sequences:  A055579 A055580 A055581 * A055583 A055584 A055585

KEYWORD

easy,nonn

AUTHOR

Wolfdieter Lang, May 26 2000

STATUS

approved

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Last modified July 11 10:48 EDT 2020. Contains 335626 sequences. (Running on oeis4.)