login
A301885
Number of 2Xn 0..1 arrays with every element equal to 0, 1 or 3 horizontally or antidiagonally adjacent elements, with upper left element zero.
2
2, 5, 10, 18, 35, 74, 154, 317, 658, 1370, 2851, 5930, 12338, 25677, 53434, 111194, 231395, 481538, 1002090, 2085365, 4339682, 9030962, 18793603, 39109842, 81388322, 169370645, 352463530, 733483298, 1526392675, 3176452154, 6610257274
OFFSET
1,1
COMMENTS
Row 2 of A301884.
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) +a(n-3) -a(n-4) -2*a(n-6) +a(n-7)
EXAMPLE
Some solutions for n=5
..0..1..1..0..1. .0..1..1..0..1. .0..1..1..0..1. .0..1..0..0..1
..0..0..1..0..1. .0..0..1..0..0. .0..0..1..1..1. .0..1..1..0..0
CROSSREFS
Cf. A301884.
Sequence in context: A224364 A327064 A246840 * A360811 A127297 A018739
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 28 2018
STATUS
approved