A280552 Number of n X 6 0..1 arrays with no element equal to more than one of its horizontal and vertical neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

6, 194, 670, 1666, 3438, 6502, 11697, 20440, 35226, 60300, 102974, 175746, 299975, 512080, 874058, 1491286, 2542606, 4331134, 7369949, 12526488, 21265610, 36058400, 61069118, 103308602, 174569331, 294669456, 496887354, 837059626

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - 12*a(n-2) + 5*a(n-3) + 12*a(n-4) - 12*a(n-5) - 3*a(n-6) + 6*a(n-7) - a(n-9) for n>12.

Empirical g.f.: x*(6 + 158*x - 422*x^2 - 56*x^3 + 440*x^4 + 260*x^5 - 83*x^6 - 314*x^7 + 22*x^8 - 45*x^9 - 142*x^10 + 4*x^11) / ((1 - x)^3*(1 - x - x^2)^3). - Colin Barker, Feb 13 2019

Example

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

Crossrefs

Column 6 of A280554.

Sequence in context: A156122 A281501 A283884 * A241137 A086065 A200824

Adjacent sequences: A280549 A280550 A280551 * A280553 A280554 A280555

Keyword

nonn

Author

R. H. Hardin, Jan 05 2017

Status

approved