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 A271896 #10 May 02 2017 06:11:44
%S A271896 1,2,4,10,28,78,212,570,1532,4126,11124,29994,80860,217966,587540,
%T A271896 1583770,4269244,11508286,31022004,83623562,225417372,607639694,
%U A271896 1637966164,4415335674,11902070652,32083468894,86484865012,233130398186,628431143260,1694012042158,4566414045076,12309320542554
%N A271896 Expansion of (x-1)^2 / ( 1-4*x+5*x^2-4*x^3 ).
%C A271896 Sum of all first elements at level n of the TRIP-Stern sequence corresponding to the permutation triple (e,e,e)
%H A271896 G. C. Greubel, <a href="/A271896/b271896.txt">Table of n, a(n) for n = 0..1000</a>
%H A271896 Ilya Amburg, Krishna Dasaratha, Laure Flapan, Thomas Garrity, Chansoo Lee, Cornelia Mihaila, Nicholas Neumann-Chun, Sarah Peluse, Matthew Stoffregen, <a href="http://arxiv.org/abs/1509.05239">Stern Sequences for a Family of Multidimensional Continued Fractions: TRIP-Stern Sequences</a>, arXiv:1509.05239 [math.CO], 2015, Section 7.2.1
%H A271896 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (4,-5,4).
%t A271896 CoefficientList[Series[(x - 1)^2/(1 - 4*x + 5*x^2 - 4*x^3), {x,0,50}], x] (* _G. C. Greubel_, May 01 2017 *)
%o A271896 (PARI) x='x+O('x^99); Vec((x-1)^2/(1-4*x+5*x^2-4*x^3)) \\ _Altug Alkan_, Apr 16 2016
%Y A271896 Cf. A000930 (maximum at level n).
%K A271896 nonn,easy
%O A271896 0,2
%A A271896 _R. J. Mathar_, Apr 16 2016