A280481 Number of 2 X n 0..2 arrays with no element unequal to a strict majority 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, 22, 63, 162, 381, 884, 1995, 4478, 9913, 21832, 47687, 103666, 224117, 482556, 1034819, 2211686, 4712113, 10011696, 21217471, 44862298, 94656621, 199333092, 419016123, 879354062, 1842593961, 3855445784, 8056377655, 16813670338

Offset

1,2

Links

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

Formula

Empirical: a(n) = 5*a(n-1) - 4*a(n-2) - 14*a(n-3) + 19*a(n-4) + 13*a(n-5) - 22*a(n-6) - 4*a(n-7) + 8*a(n-8) for n>10.

Empirical g.f.: x^2*(6 - 8*x - 23*x^2 + 19*x^3 + 17*x^4 + 13*x^5 + 16*x^6 - 16*x^7 - 40*x^8) / ((1 - x)^2*(1 + x)^3*(1 - 2*x)^3). - Colin Barker, Feb 13 2019

Example

Some solutions for n=4:
..0..0..0..1. .0..1..0..0. .0..0..1..1. .0..1..1..1. .0..0..1..2
..0..1..1..1. .1..0..0..0. .0..2..2..2. .1..2..2..2. .0..1..1..1

Crossrefs

Row 2 of A280480.

Sequence in context: A258474 A120477 A053739 * A055797 A001925 A002663

Adjacent sequences: A280478 A280479 A280480 * A280482 A280483 A280484

Keyword

nonn

Author

R. H. Hardin, Jan 04 2017

Status

approved