A302724 Number of nX3 0..1 arrays with every element equal to 1, 2, 4 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

1, 7, 22, 83, 301, 1079, 4064, 15183, 55012, 207349, 770421, 2830250, 10617371, 39400644, 145704104, 544623685, 2020998479, 7497256552, 27957348859, 103787074017, 385563034716, 1435728019366, 5332352333196, 19821039046245

Offset: 1

Author

R. H. Hardin, Apr 12 2018

Keywords

• nonn

Comments

Column 3 of A302728.

Examples

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

Links

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

Crossrefs

Cf. A302728.

Formula

Empirical: a(n) = 2*a(n-1) +5*a(n-2) +27*a(n-3) -64*a(n-4) -67*a(n-5) +25*a(n-6) -22*a(n-7) -66*a(n-8) -240*a(n-9) +232*a(n-10) +168*a(n-11) -16*a(n-12) +64*a(n-13) +64*a(n-14) +256*a(n-15) -256*a(n-16)