login
A303183
Number of 3Xn 0..1 arrays with every element equal to 0, 1, 2, 5 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.
1
4, 25, 31, 72, 170, 382, 873, 2013, 4618, 10598, 24347, 55915, 128406, 294906, 677293, 1555481, 3572366, 8204410, 18842487, 43274223, 99384898, 228250358, 524206673, 1203908917, 2764933650, 6350030286, 14583671731, 33493301843, 76921730606
OFFSET
1,1
COMMENTS
Row 3 of A303182.
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) -2*a(n-2) +2*a(n-3) -3*a(n-4) +a(n-5) for n>9
EXAMPLE
Some solutions for n=5
..0..1..0..1..1. .0..1..0..0..0. .0..0..0..1..0. .0..1..0..1..1
..1..0..1..0..0. .0..1..1..0..1. .1..1..1..1..0. .1..0..0..1..0
..1..0..1..0..1. .0..0..1..0..1. .0..1..0..1..1. .0..1..0..1..1
CROSSREFS
Cf. A303182.
Sequence in context: A042889 A042177 A302416 * A175052 A370575 A240164
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 19 2018
STATUS
approved