This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A239266 Number of domicule tilings of a 4 X n grid. 2
 1, 1, 11, 43, 280, 1563, 9415, 55553, 331133, 1968400, 11716601, 69716257, 414898579, 2469046811, 14693544104, 87442204835, 520375602855, 3096794588441, 18429266069421, 109673987617376, 652678415082545, 3884139865306433, 23114817718082715, 137558073518189643 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS A domicule is either a domino or it is formed by the union of two neighboring unit squares connected via their corners.  In a tiling the connections of two domicules are allowed to cross each other. LINKS Alois P. Heinz, Table of n, a(n) for n = 0..1000 FORMULA G.f.: -(x-1)*(x^3-x^2+5*x-1)/(5*x^6-11*x^5+30*x^4-30*x^3-2*x^2+7*x-1). EXAMPLE a(2) = 11:   +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+   |o o| |o o| |o o| |o-o| |o o| |o-o| |o o| |o o| |o-o| |o-o| |o-o|   | X | | X | | X | |   | || || |   | || || || || |   | |   | |   |   |o o| |o o| |o o| |o o| |o o| |o-o| |o o| |o o| |o-o| |o-o| |o o|   |   | |   | |   | | X | |   | |   | |   | |   | |   | |   | || ||   |o o| |o o| |o-o| |o o| |o o| |o o| |o o| |o-o| |o o| |o-o| |o o|   | X | || || |   | |   | | X | | X | || || |   | || || |   | |   |   |o o| |o o| |o-o| |o-o| |o o| |o o| |o o| |o-o| |o o| |o-o| |o-o|   +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+. MAPLE gf:= -(x-1)*(x^3-x^2+5*x-1)/(5*x^6-11*x^5+30*x^4-30*x^3-2*x^2+7*x-1): a:= n-> coeff(series(gf, x, n+1), x, n): seq(a(n), n=0..30); CROSSREFS Column k=4 of A239264. Sequence in context: A201714 A269422 A259798 * A259963 A201991 A010819 Adjacent sequences:  A239263 A239264 A239265 * A239267 A239268 A239269 KEYWORD nonn,easy AUTHOR Alois P. Heinz, Mar 13 2014 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified March 21 01:18 EDT 2019. Contains 321356 sequences. (Running on oeis4.)