A053022 Number of subdiagonal directed diagonally-convex animals with given diagonal semiperimeter.

1, 1, 3, 9, 30, 107, 396, 1506, 5848, 23087, 92381, 373830, 1527192, 6290054, 26090780, 108895558, 456992576, 1927176941, 8162557837, 34708427777, 148110582311, 634074235584, 2722547715302, 11721572763762, 50591504811439

Offset

2,3

References

F. Ibn-Majdoub-Hassani, Generating functions for directed animals convex following their direction, In: Actes du Seminaire Lotharingien de Combinatoire, 33rd session. Publication de l'IRMA, Strasbourg, France, 1994.

F. Ibn-Majdoub-Hassani, Combinatorics of polyominoes and oscillating shifted tableaux. Phd Thesis. Laboratoire de Recherche en Informatique, Univ. Paris-Sud, France, 1996

Links

Table of n, a(n) for n=2..26.

Seminaire Lotharingien de Combinatoire, Home page

Formula

G.f.: A(x)^4 + 2x(1 - x + x^2)A(x)^3 + x( - 1 + 3x - 7x^2 + 5x^3 - 2x^4 + x^5)A(x)^2 + x^3(2 - 5x + 6x^2 - 3x^3 + 2x^4)A(x) + x^5( - 1 + 2x - x^2 + x^3) = 0.

Crossrefs

Sequence in context: A024332 A036727 A216454 * A369440 A128725 A099783

Adjacent sequences: A053019 A053020 A053021 * A053023 A053024 A053025

Keyword

nonn

Author

Fouad IBN MAJDOUB HASSANI, Feb 24 2000

Extensions

More terms from Vladeta Jovovic, Mar 27 2001

Status

approved