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A093119 Number of convex polyominoes with a 3 x n+1 minimal bounding rectangle. 1
13, 68, 222, 555, 1171, 2198, 3788, 6117, 9385, 13816, 19658, 27183, 36687, 48490, 62936, 80393, 101253, 125932, 154870, 188531, 227403, 271998, 322852, 380525, 445601, 518688, 600418, 691447, 792455, 904146, 1027248, 1162513 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..32.

V. J. W. Guo and J. Zeng, The number of convex polyominoes and the generating function of Jacobi polynomials.

FORMULA

(3n+2)/(n+2)*C(2n+4, 4) - 4n/(n+2)*C(n+2, n)^2, n>0.

(1/6) (6n^4 + 20n^3 + 27n^2 + 19n + 6).

CROSSREFS

Row 2 of triangle A093118.

Sequence in context: A137720 A199896 A213355 * A156794 A137188 A055338

Adjacent sequences:  A093116 A093117 A093118 * A093120 A093121 A093122

KEYWORD

nonn,tabl

AUTHOR

Ralf Stephan, Mar 21 2004

STATUS

approved

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Last modified May 22 10:58 EDT 2013. Contains 225526 sequences.