A301611 Number of nX4 0..1 arrays with every element equal to 1, 2 or 3 horizontally or vertically adjacent elements, with upper left element zero.

2, 34, 367, 3816, 40085, 421025, 4422826, 46459647, 488047397, 5126802206, 53855652961, 565739028561, 5942934438842, 62428910463417, 655798724558441, 6888987247456952, 72366937453302201, 760194996499019669

Offset: 1

Author

R. H. Hardin, Mar 24 2018

Keywords

• nonn

Comments

Column 4 of A301615.

Examples

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

Links

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

Crossrefs

Cf. A301615.

Formula

Empirical: a(n) = 7*a(n-1) +41*a(n-2) -12*a(n-3) -318*a(n-4) -262*a(n-5) +724*a(n-6) +1034*a(n-7) -1340*a(n-8) -3422*a(n-9) +4016*a(n-10) +12158*a(n-11) +6925*a(n-12) -17989*a(n-13) -30269*a(n-14) +7574*a(n-15) +1694*a(n-16) +8004*a(n-17) -672*a(n-18) +432*a(n-19) -864*a(n-20) for n>21