A297507 Number of 2 X n 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 1 or 2 neighboring 1s.

1, 10, 31, 68, 218, 729, 2097, 6139, 18932, 57273, 170792, 514608, 1554993, 4677797, 14071941, 42401182, 127713015, 384477424, 1157762858, 3486768241, 10499588277, 31616525407, 95208917296, 286707283257, 863361068252, 2599853035248

Offset

1,2

Links

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

Formula

Empirical: a(n) = 3*a(n-1) - 2*a(n-2) + 9*a(n-3) - 6*a(n-4) - 8*a(n-5).

Empirical g.f.: x*(1 + 7*x + 3*x^2 - 14*x^3 - 8*x^4) / (1 - 3*x + 2*x^2 - 9*x^3 + 6*x^4 + 8*x^5). - Colin Barker, Feb 28 2019

Example

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

Crossrefs

Row 2 of A297506.

Sequence in context: A059306 A192023 A219693 * A163655 A041190 A111500

Adjacent sequences: A297504 A297505 A297506 * A297508 A297509 A297510

Keyword

nonn

Author

R. H. Hardin, Dec 31 2017

Status

approved