A297316 Number of 3Xn 0..1 arrays with every 1 horizontally or antidiagonally adjacent to 1 or 2 neighboring 1s.

1, 21, 117, 497, 2577, 13937, 72541, 375054, 1951949, 10170792, 52930039, 275412159, 1433386475, 7460147264, 38825258091, 202060807970, 1051605128451, 5472968149750, 28483454530439, 148239012444720, 771493812884305

Offset: 1

Author

R. H. Hardin, Dec 28 2017

Keywords

• nonn

Comments

Row 3 of A297314.

Examples

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

Links

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

Crossrefs

Cf. A297314.

Formula

Empirical: a(n) = 5*a(n-1) -7*a(n-2) +42*a(n-3) -20*a(n-4) +120*a(n-5) -109*a(n-6) +179*a(n-7) -371*a(n-8) +53*a(n-9) +390*a(n-10) -408*a(n-11) +204*a(n-12) -101*a(n-13) -43*a(n-14) +151*a(n-15) -139*a(n-16) +61*a(n-17) +2*a(n-18) -21*a(n-19) +15*a(n-20) -2*a(n-21) -a(n-22) +a(n-23)