A295411 Number of n X 3 0..1 arrays with each 1 horizontally or vertically adjacent to 1, 2 or 3 1s.

4, 36, 234, 1534, 10291, 68613, 457178, 3048314, 20323497, 135493938, 903332290, 6022478907, 40151569213, 267688593389, 1784667144371, 11898290761269, 79325337411332, 528858244821419, 3525872716944031, 23506825387232109

Offset: 1

Author

R. H. Hardin, Nov 22 2017

Keywords

• nonn

Examples

			Some solutions for n=5:
..0..1..1. .1..1..1. .1..1..0. .1..0..1. .0..1..0. .0..1..0. .1..0..1
..1..1..1. .1..0..0. .1..1..0. .1..0..1. .1..1..1. .0..1..1. .1..0..1
..1..0..0. .1..0..0. .0..0..0. .0..1..1. .1..0..0. .0..1..1. .1..0..1
..0..1..0. .1..1..1. .1..0..0. .0..1..1. .0..1..1. .0..1..0. .1..0..1
..1..1..1. .1..0..1. .1..1..0. .1..1..0. .0..1..0. .0..0..0. .0..1..1
		

Links

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

Crossrefs

Column 3 of A295416.

Formula

Empirical: a(n) = 6*a(n-1) + 28*a(n-3) + 3*a(n-4) + 49*a(n-5) + 33*a(n-6) - 34*a(n-7) - 22*a(n-8).

Empirical g.f.: x*(4 + 12*x + 18*x^2 + 18*x^3 + 67*x^4 + 11*x^5 - 50*x^6 - 22*x^7) / (1 - 6*x - 28*x^3 - 3*x^4 - 49*x^5 - 33*x^6 + 34*x^7 + 22*x^8). - Colin Barker, Feb 22 2019