A303457 Number of 3Xn 0..1 arrays with every element equal to 0, 1, 2, 3, 4 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.

4, 32, 232, 1690, 12340, 90112, 658204, 4807732, 35118024, 256519346, 1873747524, 13686804048, 99975389852, 730271188300, 5334272943080, 38964248230442, 284614727917460, 2078971032009920, 15185864006789660, 110925290484682724

Offset: 1

Author

R. H. Hardin, Apr 24 2018

Keywords

• nonn

Comments

Row 3 of A303456.

Examples

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

Links

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

Crossrefs

Cf. A303456.

Formula

Empirical: a(n) = 8*a(n-1) -40*a(n-3) +20*a(n-4) +8*a(n-5) -3*a(n-6) +32*a(n-7) for n>8