A297458 Number of 2 X n 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 0 or 2 neighboring 1s.

4, 8, 25, 57, 156, 384, 1009, 2545, 6580, 16760, 43081, 110121, 282444, 722928, 1852705, 4744417, 12155236, 31132904, 79753849, 204285465, 523300860, 1340442720, 3433646161, 8795417041, 22530001684, 57711669848, 147831676585

Offset

1,1

Links

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

Formula

Empirical: a(n) = a(n-1) + 3*a(n-2) + a(n-3) + 4*a(n-4).

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

Example

Some solutions for n=7:
..0..0..1..1..0..0..1. .0..0..1..1..0..0..0. .0..0..0..1..0..0..0
..1..0..1..1..0..0..0. .0..0..1..1..0..1..0. .0..1..0..0..0..1..0

Crossrefs

Row 2 of A297457.

Sequence in context: A068367 A292548 A000964 * A328038 A107840 A046736

Adjacent sequences: A297455 A297456 A297457 * A297459 A297460 A297461

Keyword

nonn

Author

R. H. Hardin, Dec 30 2017

Status

approved