login
A303198
Number of 3Xn 0..1 arrays with every element equal to 0, 1, 3, 5 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.
1
4, 6, 12, 23, 43, 105, 233, 479, 968, 2146, 4683, 9928, 20709, 44652, 96244, 205631, 435063, 930935, 1994977, 4266607, 9080728, 19396626, 41471567, 88657284, 189124509, 403873550, 862832200, 1843730503, 3936307111, 8406314159
OFFSET
1,1
COMMENTS
Row 3 of A303197.
LINKS
FORMULA
Empirical: a(n) = a(n-1) +a(n-2) +12*a(n-4) -6*a(n-5) -7*a(n-6) -3*a(n-7) -26*a(n-8) +9*a(n-9) +14*a(n-10) +5*a(n-11) +18*a(n-12) -5*a(n-13) -9*a(n-14) -2*a(n-15) -3*a(n-16) +a(n-17) +a(n-18) for n>19
EXAMPLE
Some solutions for n=5
..0..0..1..0..1. .0..1..0..1..0. .0..1..0..1..1. .0..1..1..1..0
..0..1..0..0..1. .0..1..0..0..0. .1..1..0..0..0. .0..1..0..0..0
..0..1..0..1..0. .0..1..0..1..0. .0..1..0..1..0. .0..1..0..1..0
CROSSREFS
Cf. A303197.
Sequence in context: A098145 A307189 A054167 * A120211 A308471 A357809
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 19 2018
STATUS
approved