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

1,2

Comments

Column 3 of A301669.

Links

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

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)

Example

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

Crossrefs

Cf. A301669.

Sequence in context: A245428 A307307 A185829 * A335803 A259136 A098684

Adjacent sequences: A301661 A301662 A301663 * A301665 A301666 A301667

Keyword

nonn

Author

R. H. Hardin, Mar 25 2018

Status

approved