A302516 Number of 3 X n 0..1 arrays with every element equal to 0, 1, 4 or 5 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

4, 4, 11, 15, 21, 52, 118, 220, 408, 852, 1764, 3460, 6796, 13732, 27708, 55140, 109788, 220132, 441244, 881380, 1760796, 3523812, 7051548, 14098660, 28189468, 56387812, 112791324, 225564900, 451098396, 902232292, 1804527388, 3608983780

Offset: 1

Author

R. H. Hardin, Apr 09 2018

Keywords

• nonn

Comments

Row 3 of A302515.

Examples

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

Links

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

Crossrefs

Cf. A302515.

Formula

Empirical: a(n) = a(n-1) +2*a(n-3) +4*a(n-4) for n>7.