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

1,2

Links

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

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

Example

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

Crossrefs

Row 3 of A281056.

Sequence in context: A054746 A116005 A297435 * A152390 A200059 A183470

Adjacent sequences: A281055 A281056 A281057 * A281059 A281060 A281061

Keyword

nonn

Author

R. H. Hardin, Jan 13 2017

Status

approved