The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A112840 Large-number statistic from the enumeration of domino tilings of a 7-pillow of order n. 3
 1, 1, 1, 1, 1, 2, 3, 7, 11, 28, 51, 154, 389, 1556, 4833, 22477, 80532, 440512, 1916580, 13388593, 73763989, 632754664, 4175659899, 42606281476, 336819337955, 4181786155008, 40981322633555, 630857431556758, 7576627032674784 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,6 COMMENTS A 7-pillow is a generalized Aztec pillow. The 7-pillow of order n is a rotationally-symmetric region. It has a 2 X 2n central band of squares and then steps up from this band with steps of 7 horizontal squares to every 1 vertical square and steps down with steps of 1 horizontal square to every 1 vertical square. REFERENCES C. Hanusa (2005). A Gessel-Viennot-Type Method for Cycle Systems with Applications to Aztec Pillows. PhD Thesis. University of Washington, Seattle, USA. LINKS EXAMPLE The number of domino tilings of the 7-pillow of order 8 is 23353=11^2*193. A112840(n)=11. CROSSREFS A112839 breaks down as A112840^2 times A112841, where A112841 is not necessarily squarefree. 3-pillows: A112833-A112835; 5-pillows: A112836-A112838; 9-pillows: A112842-A112844. Sequence in context: A107858 A214938 A143926 * A014981 A227885 A096362 Adjacent sequences:  A112837 A112838 A112839 * A112841 A112842 A112843 KEYWORD nonn AUTHOR Christopher Hanusa (chanusa(AT)math.binghamton.edu), Sep 21 2005 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 August 5 01:51 EDT 2021. Contains 346456 sequences. (Running on oeis4.)