A281566 Number of 4Xn 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, 6, 815, 3374, 12133, 31300, 67834, 136056, 264286, 498750, 924374, 1694678, 3076872, 5538752, 9905630, 17619912, 31184144, 54940940, 96415390, 168598070, 293855280, 510636866, 884919690, 1529682370, 2638054884, 4539684028

Offset

1,2

Comments

Row 4 of A281563.

Links

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

Formula

Empirical: a(n) = 6*a(n-1) -15*a(n-2) +23*a(n-3) -27*a(n-4) +21*a(n-5) -4*a(n-6) -9*a(n-7) +15*a(n-8) -14*a(n-9) +3*a(n-10) +3*a(n-11) -3*a(n-12) +3*a(n-13) -a(n-15) for n>24

Example

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

Crossrefs

Cf. A281563.

Sequence in context: A341554 A365511 A321426 * A271637 A249126 A337162

Adjacent sequences: A281563 A281564 A281565 * A281567 A281568 A281569

Keyword

nonn

Author

R. H. Hardin, Jan 24 2017

Status

approved