A281058 Number of 3 X n 0..1 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

0, 6, 68, 239, 618, 1403, 2828, 5482, 10342, 19136, 34907, 62976, 112617, 199929, 352771, 619208, 1081946, 1882951, 3265367, 5644772, 9730124, 16728760, 28693405, 49108842, 83882613, 143016171, 243420929, 413658928, 701916100, 1189400585

Offset: 1

Author

R. H. Hardin, Jan 13 2017

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Row 3 of A281056.

Formula

Empirical: a(n) = 5*a(n-1) - 7*a(n-2) - 2*a(n-3) + 10*a(n-4) - 2*a(n-5) - 5*a(n-6) + a(n-7) + a(n-8) for n>15.

Empirical g.f.: x^2*(6 + 38*x - 59*x^2 - 89*x^3 + 62*x^4 - 51*x^5 + 175*x^6 + 166*x^7 - 217*x^8 - 106*x^9 + 71*x^10 + 21*x^11 - 7*x^12 - x^13) / ((1 - x)^2*(1 - x - x^2)^3). - Colin Barker, Feb 15 2019