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 A092438 #17 Mar 13 2024 12:20:32 %S A092438 0,2,6,26,90,302,966,3026,9330,28502,86526,261626,788970,2375102, %T A092438 7141686,21457826,64439010,193448102,580606446,1742343626,5228079450, %U A092438 15686335502,47063200806,141197991026,423610750290,1270865805302 %N A092438 Sequence arising from enumeration of domino tilings of Aztec Pillow-like regions. %D A092438 J. Propp, Enumeration of matchings: problems and progress, pp. 255-291 in L. J. Billera et al., eds, New Perspectives in Algebraic Combinatorics, Cambridge, 1999 (see Problem 13). %H A092438 J. Propp, <a href="http://faculty.uml.edu/jpropp/articles.html">Publications and Preprints</a> %H A092438 J. Propp, Enumeration of matchings: problems and progress, in L. J. Billera et al. (eds.), <a href="http://www.msri.org/publications/books/Book38/contents.html">New Perspectives in Algebraic Combinatorics</a> %H A092438 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (5,-5,-5,6). %F A092438 a(n) = A092437(n, n+1). %F A092438 a(n) = A046717(n+1)-2^(n+1)+1. %F A092438 a(n) = (3^(n+1)+(-1)^(n+1))/2-2^(n+1)+1. %F A092438 From _R. J. Mathar_, Apr 21 2010: (Start) %F A092438 a(n) = +5*a(n-1) -5*a(n-2) -5*a(n-3) +6*a(n-4) = 2*A140420(n). %F A092438 G.f.: -2*x*(1-2*x+3*x^2) / ( (x-1)*(3*x-1)*(2*x-1)*(1+x) ). (End) %e A092438 a(3) = (3^4+(-1)^4)/2-2^4+1 = 26. %Y A092438 Cf. A046717, A092437-A092443, A140420. %K A092438 easy,nonn %O A092438 0,2 %A A092438 Christopher Hanusa (chanusa(AT)math.washington.edu), Mar 24 2004