A281207 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 one element, and with new values introduced in order 0 sequentially upwards.

0, 10, 56, 98, 176, 310, 537, 922, 1573, 2672, 4524, 7640, 12875, 21658, 36375, 61006, 102184, 170954, 285693, 476954, 795497, 1325596, 2207076, 3671788, 6103951, 10139930, 16833147, 27926522, 46302368, 76725022, 127066209, 210326170

Offset

1,2

Links

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

Formula

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

Empirical g.f.: x^2*(10 + 26*x - 60*x^2 - 32*x^3 + 38*x^4 + 11*x^5 - 5*x^6) / ((1 - x)*(1 - x - x^2)^2). - Colin Barker, Feb 18 2019

Example

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

Crossrefs

Row 3 of A281205.

Sequence in context: A261848 A000814 A202071 * A228888 A137931 A053493

Adjacent sequences: A281204 A281205 A281206 * A281208 A281209 A281210

Keyword

nonn

Author

R. H. Hardin, Jan 17 2017

Status

approved