A281930 Number of n X 2 0..1 arrays with no element equal to more than four of its king-move neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

0, 0, 1, 6, 33, 166, 792, 3654, 16455, 72774, 317367, 1368608, 5848140, 24799548, 104488541, 437818374, 1825747245, 7581746154, 31368531456, 129358242306, 531886946515, 2181210602118, 8923564277475, 36428064156772, 148413344768244

Offset

1,4

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - 3*a(n-2) - 14*a(n-3) - 21*a(n-4) - 12*a(n-5) - 4*a(n-6).

Empirical g.f.: x^3 / (1 - 3*x - 3*x^2 - 2*x^3)^2. - Colin Barker, Feb 20 2019

Example

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

Crossrefs

Column 2 of A281936.

Sequence in context: A240880 A099432 A072260 * A282371 A291004 A203155

Adjacent sequences: A281927 A281928 A281929 * A281931 A281932 A281933

Keyword

nonn

Author

R. H. Hardin, Feb 02 2017

Status

approved