A231951 - OEIS

A231951

Number of (n+1) X (2+1) 0..1 arrays with every element equal to some horizontal, vertical, diagonal or antidiagonal neighbor, with top left element zero.

18, 142, 1034, 7756, 58350, 438540, 3295580, 24766738, 186126146, 1398767358, 10511956032, 78999000742, 593689902080, 4461672883324, 33530172645330, 251984515016934, 1893703217109050, 14231477177253100, 106951786751372582

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OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 7*a(n-1) + 2*a(n-2) + 13*a(n-3) + 8*a(n-4).

Empirical g.f.: 2*x*(9 + 8*x + 2*x^2) / (1 - 7*x - 2*x^2 - 13*x^3 - 8*x^4). - Colin Barker, Oct 01 2018

EXAMPLE

Some solutions for n=5:

..0..1..1....0..1..0....0..1..1....0..0..1....0..0..0....0..0..0....0..0..1

..0..1..0....0..0..1....1..0..1....0..1..0....1..0..0....1..0..1....1..1..0

..0..1..0....1..0..0....1..1..0....0..1..1....1..1..0....1..1..1....0..0..0

..0..0..1....1..1..1....1..0..1....0..1..0....1..0..1....1..0..1....0..0..1

..1..0..1....1..0..0....1..0..0....1..0..0....0..1..0....1..0..0....1..0..1

..1..1..0....1..1..0....0..0..0....0..1..0....1..0..1....1..1..0....1..0..0

CROSSREFS

Column 2 of A231957.

Sequence in context: A299723 A125355 A299834 * A126513 A232820 A143992

Adjacent sequences: A231948 A231949 A231950 * A231952 A231953 A231954

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 15 2013

STATUS

approved