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Number of Baxter matrices of size 3 X n that contain n+2 1's.
2

%I #24 Aug 20 2022 10:06:47

%S 1,8,26,55,96,149,214,291,380,481,594,719,856,1005,1166,1339,1524,

%T 1721,1930,2151,2384,2629,2886,3155,3436,3729,4034,4351,4680,5021,

%U 5374,5739,6116,6505,6906,7319,7744,8181,8630,9091,9564,10049,10546,11055,11576,12109

%N Number of Baxter matrices of size 3 X n that contain n+2 1's.

%C Row 3 of array A347676.

%H Michael S. Branicky, <a href="/A347677/b347677.txt">Table of n, a(n) for n = 1..65</a>

%H George Spahn, <a href="https://arxiv.org/abs/2110.09688">Counting Baxter Matrices</a>, arXiv:2110.09688 [math.CO], 2021.

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1)

%F a(n) = 6*n^2 - 13*n + 11 for n >= 3. - _George Spahn_, Oct 20 2021

%F g.f.: x+8*x^2 -x^3 *(26-23*x+9*x^2)/(x-1)^3 . - _R. J. Mathar_, Aug 20 2022

%Y Cf. A347676, A347673.

%K nonn,easy

%O 1,2

%A _N. J. A. Sloane_, Sep 10 2021

%E a(8)-a(46) from _Michael S. Branicky_, Sep 13 2021