A230942 Number of (n+3) X (1+3) 0..3 white square subarrays x(i,j) with each element diagonally or antidiagonally next to at least one element with value (x(i,j)+1) mod 4, and upper left element zero.

6, 16, 76, 314, 1170, 4584, 18208, 71242, 278758, 1094600, 4294812, 16840082, 66052162, 259099696, 1016260448, 3986056882, 15634778470, 61325029216, 240537044748, 943467829258, 3700602618386, 14515016732376, 56932811822272

Offset

1,1

Comments

Column 1 of A230949.

Links

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

Formula

Empirical: a(n) = 3*a(n-1) + 14*a(n-3) + a(n-4) - a(n-5).

Empirical g.f.: 2*x*(3 - x + 14*x^2 + x^3 - x^4) / (1 - 3*x - 14*x^3 - x^4 + x^5). - Colin Barker, Mar 18 2018

Example

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

Crossrefs

Cf. A230949.

Sequence in context: A083885 A350649 A211954 * A188570 A009352 A056204

Adjacent sequences: A230939 A230940 A230941 * A230943 A230944 A230945

Keyword

nonn

Author

R. H. Hardin, Nov 01 2013

Status

approved