A229536 Number of defective 3-colorings of a 3 X n 0..2 array connected horizontally, diagonally and antidiagonally with exactly one mistake, and colors introduced in row-major 0..2 order.

0, 20, 58, 361, 1588, 7460, 33136, 146300, 634976, 2729872, 11628320, 49175856, 206658752, 863838624, 3594073792, 14892589280, 61487645824, 253053701600, 1038460551744, 4250534994848, 17357200322560, 70727788661344

Offset

1,2

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - a(n-2) - 28*a(n-3) - 4*a(n-4) + 16*a(n-5) - 4*a(n-6) for n>8.

Empirical g.f.: x^2*(20 - 62*x + 33*x^2 + 40*x^3 - 3*x^4 - 16*x^5 + 4*x^6) / (1 - 3*x - 4*x^2 + 2*x^3)^2. - _Colin Barker_, Sep 18 2018

Example

Some solutions for n=4:
..0..1..0..1....0..1..0..2....0..1..2..1....0..1..2..1....0..1..2..1
..0..2..0..2....0..2..1..2....0..1..0..1....0..1..2..1....2..0..2..1
..2..1..0..1....0..2..0..2....2..2..0..1....2..0..2..0....2..0..2..1

Crossrefs

Row 3 of A229534.

Sequence in context: A069132 A124713 A126374 * A220013 A220046 A275167

Adjacent sequences: A229533 A229534 A229535 * A229537 A229538 A229539

Keyword

nonn

Author

_R. H. Hardin_, Sep 25 2013

Status

approved