login
A303526
Number of 3Xn 0..1 arrays with every element equal to 0, 1, 3, 4, 5 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.
1
4, 6, 18, 37, 80, 286, 916, 2532, 7477, 24285, 76820, 235117, 731307, 2316410, 7294592, 22810317, 71569571, 225378484, 708826544, 2225946457, 6995090976, 21998860077, 69164809009, 217385283885, 683342646350, 2148402980261
OFFSET
1,1
COMMENTS
Row 3 of A303525.
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) +3*a(n-2) +a(n-3) +30*a(n-4) -53*a(n-5) -102*a(n-6) +11*a(n-7) -227*a(n-8) +351*a(n-9) +784*a(n-10) -242*a(n-11) +351*a(n-12) -361*a(n-13) -1069*a(n-14) +577*a(n-15) +8*a(n-16) +28*a(n-17) +22*a(n-18) -11*a(n-19) -a(n-20) for n>21
EXAMPLE
Some solutions for n=5
..0..0..0..1..0. .0..1..0..0..0. .0..0..1..0..1. .0..1..1..0..1
..0..1..1..1..0. .0..1..1..1..0. .1..1..1..0..1. .1..0..1..0..1
..0..1..0..1..0. .0..0..0..1..0. .1..0..0..0..1. .1..0..1..0..1
CROSSREFS
Cf. A303525.
Sequence in context: A107390 A051253 A175955 * A064403 A235344 A060667
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 25 2018
STATUS
approved