A281211 Number of 7 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, 1308, 2688, 3604, 5712, 9118, 14375, 22700, 36144, 58168, 94524, 154800, 254959, 421560, 698756, 1159898, 1926760, 3201376, 5318733, 8833940, 14666360, 24337820, 40366132, 66914912, 110866187, 183590176, 303864300, 502685950, 831204864

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>13.

Empirical g.f.: x^2*(1308 - 2544*x - 1916*x^2 + 4664*x^3 + 830*x^4 - 2793*x^5 - 12*x^6 + 920*x^7 + 274*x^8 + 40*x^9 - 18*x^10 - 10*x^11) / ((1 - x)^2*(1 - x - x^2)^2). - Colin Barker, Feb 18 2019

Example

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

Crossrefs

Row 7 of A281205.

Sequence in context: A126841 A106815 A325605 * A233975 A209853 A165936

Adjacent sequences: A281208 A281209 A281210 * A281212 A281213 A281214

Keyword

nonn

Author

R. H. Hardin, Jan 17 2017

Status

approved