A208633 Number of n X 4 0..1 arrays with new values 0..1 introduced in row major order and no element equal to more than one of its immediate leftward or upward or right-upward antidiagonal neighbors.

8, 23, 71, 225, 722, 2331, 7548, 24476, 79423, 257807, 836973, 2717446, 8823199, 28648292, 93019712, 302032007, 980690055, 3184277945, 10339281402, 33571429395, 109005736508, 353939387572, 1149233948207, 3731539152111

Offset

1,1

Comments

Column 4 of A208637.

Links

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

Formula

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

Empirical g.f.: x*(8 - 17*x + 4*x^2) / (1 - 5*x + 6*x^2 - x^3). - Colin Barker, Jul 05 2018

Example

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

Crossrefs

Cf. A208637.

Sequence in context: A362163 A059209 A099274 * A036562 A320310 A303720

Adjacent sequences: A208630 A208631 A208632 * A208634 A208635 A208636

Keyword

nonn

Author

R. H. Hardin, Feb 29 2012

Status

approved