A112836 - OEIS

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A112836

Number of domino tilings of a 5-pillow of order n.

1, 2, 5, 13, 52, 261, 1666, 14400, 159250, 2308545, 43718544, 1079620569, 34863330980, 1466458546176, 80646187346132, 5787269582487581, 541901038236234048, 66279540183479379277, 10578427028263503488000

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OFFSET

0,2

COMMENTS

A 5-pillow is a generalized Aztec pillow. The 5-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 5 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

Table of n, a(n) for n=0..18.

EXAMPLE

The number of domino tilings of the 5-pillow of order 6 is 1666=7^2*34.

CROSSREFS

A112836 can be decomposed as A112837^2 times A112838, where A112838 is not necessarily squarefree.

3-pillows: A112833-A112835; 7-pillows: A112839-A112841; 9-pillows: A112842-A112844.

Sequence in context: A059103 A365709 A260709 * A353719 A353722 A105905

Adjacent sequences: A112833 A112834 A112835 * A112837 A112838 A112839

KEYWORD

nonn

AUTHOR

Christopher Hanusa (chanusa(AT)math.binghamton.edu), Sep 21 2005

STATUS

approved