A317857 Number of nX2 0..1 arrays with every element unequal to 1, 2 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.

1, 3, 6, 10, 21, 46, 102, 220, 491, 1077, 2393, 5271, 11682, 25799, 57090, 126209, 279123, 617274, 1364930, 3018713, 6675002, 14762294, 32643544, 72191407, 159639957, 353036505, 780698639, 1726457594, 3817890631, 8442936930

Offset

1,2

Comments

Column 2 of A317863.

Links

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

Formula

Empirical: a(n) = a(n-1) +4*a(n-2) -2*a(n-3) -2*a(n-4) +a(n-5) -4*a(n-6) +4*a(n-7) -a(n-8)

Example

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

Crossrefs

Cf. A317863.

Sequence in context: A068709 A068804 A117834 * A346733 A220827 A063015

Adjacent sequences: A317854 A317855 A317856 * A317858 A317859 A317860

Keyword

nonn

Author

R. H. Hardin, Aug 09 2018

Status

approved