

A112842


Number of domino tilings of a 9pillow of order n.


13



1, 2, 5, 13, 34, 89, 356, 1737, 9065, 49610, 325832, 2795584, 28098632, 310726442, 3877921669, 58896208285, 1083370353616, 22901813128125, 548749450880000, 15471093192996501, 522297110942557556, 20691062026775504896
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OFFSET

0,2


COMMENTS

A 9pillow is a generalized Aztec pillow. The 9pillow 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 9 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..21.


EXAMPLE

The number of domino tilings of the 9pillow of order 8 is 9065=7^2*185.


CROSSREFS

A112842 breaks down as A112843^2 times A112844, where A112844 is not necessarily squarefree.
3pillows: A112833A112835; 5pillows: A112836A112838; 7pillows: A112839A112841.
Sequence in context: A099496 A122367 A114299 * A097417 A006801 A114173
Adjacent sequences: A112839 A112840 A112841 * A112843 A112844 A112845


KEYWORD

nonn


AUTHOR

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


STATUS

approved



