A301843 Number of 3Xn 0..1 arrays with every element equal to 0, 1 or 2 horizontally or antidiagonally adjacent elements, with upper left element zero.

4, 32, 139, 678, 3182, 15199, 72514, 346244, 1653214, 7893443, 37688062, 179946317, 859175558, 4102237937, 19586633161, 93518758201, 446516665710, 2131948036306, 10179244758257, 48602040050313, 232056341426270, 1107981178164225

Offset

1,1

Comments

Row 3 of A301841.

Links

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

Formula

Empirical: a(n) = 4*a(n-1) +3*a(n-2) +3*a(n-3) +2*a(n-4) -2*a(n-5) +2*a(n-6) -7*a(n-7) -3*a(n-8) +5*a(n-9) -4*a(n-10) -3*a(n-11) +a(n-12) for n>14

Example

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

Crossrefs

Cf. A301841.

Sequence in context: A088658 A088802 A123854 * A332430 A302070 A302267

Adjacent sequences: A301840 A301841 A301842 * A301844 A301845 A301846

Keyword

nonn

Author

R. H. Hardin, Mar 27 2018

Status

approved