A229577 Number of defective 4-colorings of an n X 7 0..3 array connected horizontally, vertically, diagonally and antidiagonally with exactly one mistake, and colors introduced in row-major 0..3 order.

246, 1312, 1584, 2064, 2852, 4048, 6108, 9992, 17716, 33504, 66188, 134200, 275940, 571280, 1186108, 2464488, 5119124, 10624576, 22028268, 45621656, 94380868, 195044592, 402663068, 830482504, 1711286772, 3523226528, 7247768908

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - 13*a(n-2) + 12*a(n-3) - 4*a(n-4) for n>7.

Empirical g.f.: 2*x*(123 - 82*x - 1545*x^2 + 3332*x^3 - 1850*x^4 + 4*x^5 + 232*x^6) / ((1 - x)^2*(1 - 2*x)^2). - Colin Barker, Sep 19 2018

Example

Some solutions for n=3:
..0..1..2..1..2..1..0....0..1..0..2..3..1..0....0..1..2..1..2..1..2
..3..3..0..3..0..3..2....3..2..3..1..0..2..3....0..3..0..3..0..3..0
..2..1..2..1..2..1..0....0..1..0..2..3..2..0....2..1..2..1..2..1..2

Crossrefs

Column 7 of A229578.

Sequence in context: A231964 A231965 A067916 * A186796 A186788 A074995

Adjacent sequences: A229574 A229575 A229576 * A229578 A229579 A229580

Keyword

nonn

Author

R. H. Hardin, Sep 26 2013

Status

approved