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A112839 Number of domino tilings of a 7-pillow of order n. 13
1, 2, 5, 13, 34, 136, 666, 3577, 23353, 200704, 2062593, 24878084, 373006265, 6917185552, 153624835953, 4155902941554, 138450383756352, 5602635336941568, 274540864716936000, 16486029239132118530, 1209110712606533552257 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

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

Table of n, a(n) for n=0..20.

EXAMPLE

The number of domino tilings of the 7-pillow of order 8 is 23353=11^2*193.

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: A148290 A029885 A114298 * A137674 A048781 A097919

Adjacent sequences:  A112836 A112837 A112838 * A112840 A112841 A112842

KEYWORD

nonn

AUTHOR

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

STATUS

approved

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Last modified December 21 05:22 EST 2014. Contains 252296 sequences.