This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A112844 #4 Jun 01 2010 03:00:00 %S A112844 1,2,5,13,34,89,89,193,185,410,482,1444,2018,6362,8461,19885,22861, %T A112844 51125,59792,146749,195749,529114,730465,1907545,2350177,5638489, %U A112844 6692337,16167545,20091490,51762100,67753160,178151440,229118152 %N A112844 Small-number statistic from the enumeration of domino tilings of a 9-pillow of order n. %C A112844 A 9-pillow is a generalized Aztec pillow. The 9-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 9 horizontal squares to every 1 vertical square and steps down with steps of 1 horizontal square to every 1 vertical square. %C A112844 Plotting A112844(n+2)/A112844(n) gives an intriguing damped sine curve. %D A112844 C. Hanusa (2005). A Gessel-Viennot-Type Method for Cycle Systems with Applications to Aztec Pillows. PhD Thesis. University of Washington, Seattle, USA. %e A112844 The number of domino tilings of the 9-pillow of order 8 is 9065=7^2*185. A112844(n)=185. %Y A112844 A112842 breaks down as A112843^2 times A112844, where A112844 is not necessarily squarefree. %Y A112844 3-pillows: A112833-A112835; 5-pillows: A112836-A112838; 7-pillows: A112839-A112841. %K A112844 easy,nonn %O A112844 0,2 %A A112844 Christopher Hanusa (chanusa(AT)math.binghamton.edu), Sep 21 2005