A347677 Number of Baxter matrices of size 3 X n that contain n+2 1's.

1, 8, 26, 55, 96, 149, 214, 291, 380, 481, 594, 719, 856, 1005, 1166, 1339, 1524, 1721, 1930, 2151, 2384, 2629, 2886, 3155, 3436, 3729, 4034, 4351, 4680, 5021, 5374, 5739, 6116, 6505, 6906, 7319, 7744, 8181, 8630, 9091, 9564, 10049, 10546, 11055, 11576, 12109

Offset: 1

Author

N. J. A. Sloane, Sep 10 2021

Keywords

• nonn
• easy

Comments

Row 3 of array A347676.

Links

• Michael S. Branicky, Table of n, a(n) for n = 1..65
• George Spahn, Counting Baxter Matrices, arXiv:2110.09688 [math.CO], 2021.
• Index entries for linear recurrences with constant coefficients, signature (3,-3,1)

Crossrefs

Cf. A347676, A347673.

Formula

a(n) = 6*n^2 - 13*n + 11 for n >= 3. - George Spahn, Oct 20 2021

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

Extensions

a(8)-a(46) from Michael S. Branicky, Sep 13 2021