A297427 Number of n X 4 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 2 neighboring 1s.

1, 12, 26, 42, 183, 513, 1085, 3332, 9744, 23836, 65693, 187681, 491757, 1322824, 3682514, 9913750, 26662827, 73102697, 198448393, 535843320, 1459128416, 3966961416, 10743629897, 29183372609, 79314611625, 215140998420

Offset

1,2

Links

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

Formula

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

Empirical g.f.: x*(1 + 11*x + 14*x^2 + 4*x^3 - 5*x^4 - 8*x^5 - x^6) / (1 - x - 12*x^3 - 2*x^4 - 2*x^5 + 7*x^6 + x^7). - Colin Barker, Feb 28 2019

Example

Some solutions for n=5:
..1..1..0..0. .0..1..1..1. .0..0..1..1. .0..1..1..0. .0..1..0..0
..0..1..1..0. .0..0..1..0. .0..1..1..0. .0..1..1..0. .1..1..1..0
..0..0..0..0. .0..0..0..0. .0..0..0..0. .0..0..0..0. .0..0..0..0
..0..1..1..1. .1..1..0..0. .0..0..1..1. .0..1..1..1. .1..1..0..0
..0..0..1..0. .1..1..0..0. .0..1..1..0. .0..0..1..0. .0..1..1..0

Crossrefs

Column 4 of A297431.

Sequence in context: A184826 A119412 A105814 * A357893 A211115 A232936

Adjacent sequences: A297424 A297425 A297426 * A297428 A297429 A297430

Keyword

nonn

Author

R. H. Hardin, Dec 30 2017

Status

approved