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 A112841 Small-number statistic from the enumeration of domino tilings of a 7-pillow of order n. 12
 1, 2, 5, 13, 34, 34, 74, 73, 193, 256, 793, 1049, 2465, 2857, 6577, 8226, 21348, 28872, 74740, 91970, 222217, 268769, 669265, 852305, 2201945, 2805760, 7000777, 8636081, 21311098, 26588770, 67091170, 85150213 (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. Plotting A112841(n+2)/A112841(n) gives an intriguing damped sine curve. 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 EXAMPLE The number of domino tilings of the 7-pillow of order 8 is 23353=11^2*193. A112841(n)=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: A278134 A271940 A273721 * A104589 A154101 A122024 Adjacent sequences:  A112838 A112839 A112840 * A112842 A112843 A112844 KEYWORD easy,nonn AUTHOR Christopher Hanusa (chanusa(AT)math.binghamton.edu), Sep 21 2005 STATUS approved

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Last modified June 24 00:06 EDT 2021. Contains 345403 sequences. (Running on oeis4.)