A082398 Number of directed, diagonally convex polyominoes with n cells.

1, 0, 3, 10, 33, 106, 331, 1009, 3017, 8884, 25841, 74416, 212533, 602785, 1699503, 4767166, 13312641, 37031254, 102651967, 283676689, 781763381, 2149017256, 5894114513, 16132400860, 44071485673, 120188174401, 327242994651

Offset

1,3

References

Fouad Ibn-Majdoub-Hassani. Combinatoire de polyominos et des tableaux decales oscillants. These de Doctorat, Laboratoire de Recherche en Informatique, Universite Paris-Sud XI, France.

Links

Table of n, a(n) for n=1..27.

Formula

G.f.: (x*(1-4*x+6*x^2-3*x^3+x^4))/((1-x)*(1-3*x+x^2)^2)

Mathematica

Join[{1, 0}, Take[CoefficientList[Series[(q*(1 - 4*q + 6*q^2 - 3*q^3 + q^4))/((1 - q)*(1 - 3*q + q^2)^2), {q, 0, 27}], q], -26]]

Crossrefs

Sequence in context: A096483 A093043 A061566 * A053156 A120897 A077825

Adjacent sequences: A082395 A082396 A082397 * A082399 A082400 A082401

Keyword

nonn,easy

Author

Fouad IBN MAJDOUB HASSANI, Apr 14 2003

Extensions

More terms from Robert G. Wilson v, Apr 15 2003

Status

approved