login
A302000
Number of 3Xn 0..1 arrays with every element equal to 1, 2 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero.
1
0, 5, 5, 26, 84, 309, 1108, 3979, 14314, 51440, 185083, 665473, 2393298, 8606453, 30950505, 111303112, 400265922, 1439423515, 5176415456, 18615274437, 66943726862, 240741120250, 865746384343, 3113372499381, 11196221683404
OFFSET
1,2
COMMENTS
Row 3 of A301999.
LINKS
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..1..1..1. .0..0..0..1..1. .0..0..1..1..1. .0..0..0..1..1
..0..0..0..0..1. .1..1..1..0..1. .0..1..0..0..0. .1..1..0..1..1
..1..1..0..1..1. .0..0..0..1..1. .1..1..1..1..1. .1..0..0..1..1
CROSSREFS
Cf. A301999.
Sequence in context: A203191 A165423 A220078 * A219351 A130220 A081847
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 30 2018
STATUS
approved