A204625 - OEIS

A204625

Number of (n+1) X 4 0..2 arrays with every 2 X 2 subblock having unequal diagonal elements or unequal antidiagonal elements, and new values 0..2 introduced in row major order.

768, 43734, 2490558, 141832254, 8077061502, 459972403614, 26194503047262, 1491724252385406, 84950695233299262, 4837771196037723486, 275501337345598245918, 15689246928705157494846, 893471050128160321852158

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OFFSET

1,1

COMMENTS

Column 3 of A204630.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 60*a(n-1) - 175*a(n-2) + 68*a(n-3).

Empirical g.f.: 6*x*(128 - 391*x + 153*x^2) / (1 - 60*x + 175*x^2 - 68*x^3). - Colin Barker, Jun 07 2018

EXAMPLE

Some solutions for n=3: