A301664 Number of nX3 0..1 arrays with every element equal to 1, 2 or 4 horizontally or vertically adjacent elements, with upper left element zero.

1, 10, 30, 118, 407, 1498, 5289, 19184, 68832, 247756, 890523, 3203084, 11517675, 41422044, 148957388, 535680672, 1926390947, 6927645818, 24912983963, 89591402294, 322185988646, 1158636174394, 4166654317703, 14984004032116

Offset: 1

Author

R. H. Hardin, Mar 25 2018

Keywords

• nonn

Comments

Column 3 of A301669.

Examples

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

Links

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

Crossrefs

Cf. A301669.

Formula

Empirical: a(n) = 2*a(n-1) +6*a(n-2) -2*a(n-4) +2*a(n-5) -9*a(n-6) -50*a(n-7) -37*a(n-8) +34*a(n-9) +43*a(n-10) -16*a(n-11) +15*a(n-12) +18*a(n-13) -7*a(n-14) -2*a(n-16) +4*a(n-17) -6*a(n-18) +a(n-20)