A229754 Number of defective 4-colorings of an n X 7 0..3 array connected horizontally, vertically, diagonally and antidiagonally with exactly two mistakes, and colors introduced in row-major 0..3 order.

210, 20032, 41872, 69198, 113330, 186396, 314700, 557578, 1046550, 2070144, 4258696, 8984046, 19221426, 41402836, 89392212, 192991026, 416096878, 895389192, 1922585088, 4119014998, 8805491466, 18784661532, 39993300364

Offset

1,1

Links

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

Formula

Empirical: a(n) = 9*a(n-1) - 33*a(n-2) + 63*a(n-3) - 66*a(n-4) + 36*a(n-5) - 8*a(n-6) for n>11.

Empirical g.f.: 2*x*(105 + 9071*x - 65743*x^2 + 170088*x^3 - 187916*x^4 + 63288*x^5 + 30816*x^6 - 21756*x^7 - 2936*x^8 + 504*x^9 + 1360*x^10) / ((1 - x)^3*(1 - 2*x)^3). - Colin Barker, Sep 21 2018

Example

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

Crossrefs

Column 7 of A229755.

Sequence in context: A140904 A092711 A187308 * A089514 A289328 A014979

Adjacent sequences: A229751 A229752 A229753 * A229755 A229756 A229757

Keyword

nonn

Author

R. H. Hardin, Sep 28 2013

Status

approved