|
| |
|
|
A006027
|
|
Number of directed column-convex polyominoes with perimeter 2n+2.
(Formerly M1647)
|
|
3
| |
|
|
1, 1, 2, 6, 20, 71, 263, 1005, 3933, 15684, 63505, 260390, 1079019, 4511700, 19011521, 80653480, 344193353, 1476589475, 6364258163, 27545933212, 119676949397, 521739175908, 2281673067934, 10006784399183
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,3
|
|
|
REFERENCES
| M.-P. Delest, Utilisation des Langages Alg\'{e}briques et du Calcul Formel Pour le Codage et l'Enumeration des Polyominos. Ph.D. Dissertation, Universit\'{e} Bordeaux I, May 1987.
Delest, M.-P., Generating functions for column-convex polyominoes. J. Combin. Theory Ser. A 48 (1988), no. 1, 12-31.
M.-P. Delest and S. Dulucq, Enumeration of directed column-convex animals with given perimeter and area, Croat. Chem. Acta. 66 (1993), 59-80.
E. Duchi and S. Rinaldi, An object grammar for column-convex polyominoes, Annals of Combinatorics, 8 (2004), 27-36.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
|
|
|
FORMULA
| G.f. A(x) = a(1)x^2 + a(2)x^3 + a(3)x^4 + ... satisfies the functional equation A^3 + 2(x-1)A^2 + (2x-1)(x-1)A + (x^2)(x-1) = 0. - D. G. Rogers, May 22 2005
|
|
|
CROSSREFS
| Cf. A005435.
Sequence in context: A129777 A108600 A128729 * A049124 A163134 A150128
Adjacent sequences: A006024 A006025 A006026 * A006028 A006029 A006030
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Simon Plouffe (simon.plouffe(AT)gmail.com)
|
|
|
EXTENSIONS
| More terms from Douglas Rogers and Emanuele Munarini, May 15 2005
|
| |
|
|
