

A112838


Smallnumber statistic from the enumeration of domino tilings of a 5pillow of order n.


11



1, 2, 5, 13, 13, 29, 34, 100, 130, 305, 361, 881, 1145, 2906, 3557, 8669, 10693, 26893, 33680, 83360, 102800, 254565, 317165, 790037, 980237, 2428298, 3011265, 7483801, 9301217, 23092857, 28646722, 71093860
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OFFSET

0,2


COMMENTS

A 5pillow is a generalized Aztec pillow. The 5pillow 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 5 horizontal squares to every 1 vertical square and steps down with steps of 1 horizontal square to every 1 vertical square.
Plotting A112838(n+2)/A112838(n) gives an intriguing damped sine curve.


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..31.


EXAMPLE

The number of domino tilings of the 5pillow of order 6 is 1666=7^2*34. A112838(n)=34.


CROSSREFS

A112833 breaks down as A112834^2 times A112835, where A112835 is not necessarily squarefree.
3pillows: A112833A112835; 7pillows: A112839A112841; 9pillows: A112842A112844.
Sequence in context: A166134 A067365 A189993 * A111296 A089728 A127987
Adjacent sequences: A112835 A112836 A112837 * A112839 A112840 A112841


KEYWORD

easy,nonn


AUTHOR

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


STATUS

approved



