A281559 Number of nX4 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, 18, 621, 3374, 15508, 53568, 162919, 463916, 1262057, 3344312, 8682013, 22096236, 55418093, 137452378, 337368553, 820589074, 1981158104, 4751265748, 11325996647, 26856461774, 63380869317, 148929846348, 348578197271

Offset

1,2

Comments

Column 4 of A281563.

Links

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

Formula

Empirical: a(n) = 3*a(n-1) +7*a(n-3) -21*a(n-4) -27*a(n-5) -17*a(n-6) +84*a(n-7) +168*a(n-8) +79*a(n-9) -231*a(n-10) -480*a(n-11) -209*a(n-12) +417*a(n-13) +768*a(n-14) +266*a(n-15) -561*a(n-16) -705*a(n-17) -44*a(n-18) +468*a(n-19) +252*a(n-20) -108*a(n-21) -135*a(n-22) +27*a(n-24) for n>34

Example

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

Crossrefs

Cf. A281563.

Sequence in context: A180822 A295369 A350984 * A166767 A322889 A003298

Adjacent sequences: A281556 A281557 A281558 * A281560 A281561 A281562

Keyword

nonn

Author

R. H. Hardin, Jan 24 2017

Status

approved