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 A128445 #94 Feb 14 2024 15:00:28
%S A128445 1,1,2,8,20,40,68,104,148,200,260,328,404,488,580,680,788,904,1028,
%T A128445 1160,1300,1448,1604,1768,1940,2120,2308,2504,2708,2920,3140,3368,
%U A128445 3604,3848,4100,4360,4628,4904,5188,5480,5780,6088,6404,6728,7060,7400,7748,8104
%N A128445 Number of facets of the Alternating Sign Matrix polytope ASM(n).
%C A128445 The number of vertices (Bressoud) is Product_{j=0..n-1}(3j+1)!/(n+j)!.
%D A128445 D. M. Bressoud, Proofs and confirmations: the story of the alternating sign matrix conjecture, MAA Spectrum, 1999.
%H A128445 Jessica Striker, <a href="http://arXiv.org/abs/0705.0998">The alternating sign matrix polytope</a>, arXiv:0705.0998 [math.CO], 2007-2009.
%H A128445 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A128445 a(n) = 4*((n-2)^2 + 1) for n >= 3.
%F A128445 From _Harvey P. Dale_, Mar 05 2012: (Start)
%F A128445 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3), n > 5.
%F A128445 G.f.: (2*x^5+x^4+4*x^3+2*x^2-4*x+1)/(1-x)^3. (End)
%t A128445 Table[4((n-2)^2+1),{n,0,50}] (* or *) LinearRecurrence[{3,-3,1},{20,8,4},50] (* _Harvey P. Dale_, Mar 05 2012 *)
%o A128445 (PARI) a(n)=([0,1,0; 0,0,1; 1,-3,3]^n*[20;8;4])[1,1] \\ _Charles R Greathouse IV_, Jun 17 2017
%Y A128445 Cf. A005130 (number of vertices).
%K A128445 easy,nonn
%O A128445 0,3
%A A128445 _Jonathan Vos Post_, May 09 2007
%E A128445 More terms from _Harvey P. Dale_, Mar 05 2012
%E A128445 Initial 3 terms and formulas corrected by _Ludovic Schwob_, Feb 14 2024