A303406 Number of nX3 0..1 arrays with every element equal to 1, 2, 4, 5 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

1, 7, 28, 119, 541, 2327, 10384, 47491, 208616, 938105, 4229023, 18855226, 84609455, 379973132, 1700940358, 7627893865, 34215621269, 153337948168, 687522535009, 3082887354405, 13820286385598, 61963243406462, 277818915171978

Offset: 1

Author

R. H. Hardin, Apr 23 2018

Keywords

• nonn

Comments

Column 3 of A303410.

Examples

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

Links

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

Crossrefs

Cf. A303410.

Formula

Empirical: a(n) = 2*a(n-1) +7*a(n-2) +35*a(n-3) -36*a(n-4) -151*a(n-5) -97*a(n-6) +34*a(n-7) +258*a(n-8) -724*a(n-9) +256*a(n-10) +1584*a(n-11) -240*a(n-12) -512*a(n-13) -304*a(n-14) +1728*a(n-15) -1344*a(n-16) -1792*a(n-17) +1024*a(n-18)