A281557 Number of nX2 0..1 arrays with no element equal to more than two of its horizontal, diagonal or antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

0, 0, 1, 6, 57, 310, 1508, 6854, 29487, 122326, 493459, 1947088, 7547120, 28825124, 108734941, 405846502, 1500971233, 5506856450, 20061712660, 72628513234, 261461893675, 936516327062, 3339154281263, 11856367499652, 41938909254744

Offset

1,4

Comments

Column 2 of A281563.

Links

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

Formula

Empirical: a(n) = 9*a(n-1) -24*a(n-2) +9*a(n-3) +18*a(n-4) +45*a(n-5) -41*a(n-6) -36*a(n-7) -18*a(n-8) +36*a(n-9) +12*a(n-10) -8*a(n-12)

Example

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

Crossrefs

Cf. A281563.

Sequence in context: A083696 A288680 A181430 * A227813 A221575 A001593

Adjacent sequences: A281554 A281555 A281556 * A281558 A281559 A281560

Keyword

nonn

Author

R. H. Hardin, Jan 24 2017

Status

approved