A281210 Number of 6 X n 0..1 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.

0, 420, 1120, 1588, 2602, 4248, 6838, 11010, 17840, 29120, 47838, 78978, 130842, 217250, 361188, 600860, 999718, 1663078, 2765630, 4596962, 7636856, 12679768, 21040526, 34894090, 57836514, 95810754, 158634028, 262516660, 434214550

Offset

1,2

Links

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

Formula

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

Empirical g.f.: 2*x^2*(210 - 280*x - 606*x^2 + 785*x^3 + 376*x^4 - 525*x^5 - 39*x^6 + 180*x^7 + 36*x^8 - 6*x^9 - 3*x^10) / ((1 - x)^2*(1 - x - x^2)^2). - Colin Barker, Feb 18 2019

Example

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

Crossrefs

Row 6 of A281205.

Sequence in context: A169825 A135196 A259025 * A235233 A251084 A250383

Adjacent sequences: A281207 A281208 A281209 * A281211 A281212 A281213

Keyword

nonn

Author

R. H. Hardin, Jan 17 2017

Status

approved