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 A112834 #4 Jun 01 2010 03:00:00 %S A112834 1,1,1,2,3,8,19,76,263,1584,8199,73272,566401,7555072,87000289, %T A112834 1730799376,29728075177,881736342784,22583659690665,998900331837728, %U A112834 38149790451459859,2516220411436892160,143302702816187031875 %N A112834 Large-number statistic from the enumeration of domino tilings of a 3-pillow of order n. %C A112834 A 3-pillow is also called an Aztec pillow. The 3-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 3 horizontal squares to every 1 vertical square and steps down with steps of 1 horizontal square to every 1 vertical square. %D A112834 C. Hanusa (2005). A Gessel-Viennot-Type Method for Cycle Systems with Applications to Aztec Pillows. PhD Thesis. University of Washington, Seattle, USA. %e A112834 The number of domino tilings of the 3-pillow of order 4 is 117=3^2*13. A112834(4)=3. %Y A112834 A112833 breaks down as a(n)^2 times A112835, where A112835 is not necessarily squarefree. %Y A112834 5-pillows: A112836-A112838; 7-pillows: A112839-A112841; 9-pillows: A112842-A112844. %K A112834 nonn %O A112834 0,4 %A A112834 Christopher Hanusa (chanusa(AT)math.binghamton.edu), Sep 21 2005