

A112839


Number of domino tilings of a 7pillow 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
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OFFSET

0,2


COMMENTS

A 7pillow is a generalized Aztec pillow. The 7pillow of order n is a rotationallysymmetric 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 GesselViennotType 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 7pillow of order 8 is 23353=11^2*193.


CROSSREFS

A112839 breaks down as A112840^2 times A112841, where A112841 is not necessarily squarefree.
3pillows: A112833A112835; 5pillows: A112836A112838; 9pillows: A112842A112844.
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



