login
A202974
Number of n X 3 0..1 arrays with every nonzero element less than or equal to at least two horizontal and vertical neighbors.
1
1, 4, 17, 58, 215, 866, 3507, 14120, 56921, 229860, 928443, 3749720, 15144167, 61165438, 247041429, 997775144, 4029911351, 16276407572, 65738788527, 265512410122, 1072378133103, 4331228325504, 17493399301365, 70654095337584
OFFSET
1,2
COMMENTS
Column 3 of A202979.
LINKS
FORMULA
Empirical: a(n) = 6*a(n-1) - 11*a(n-2) + 16*a(n-3) - 14*a(n-4) - 3*a(n-5) + 8*a(n-6) - 9*a(n-7) - 2*a(n-8) + 6*a(n-9) + 2*a(n-10).
Empirical g.f.: x*(1 - 2*x + 4*x^2 - 16*x^3 + 4*x^4 + x^5 - 10*x^6 + 4*x^7 + 8*x^8 + 2*x^9) / (1 - 6*x + 11*x^2 - 16*x^3 + 14*x^4 + 3*x^5 - 8*x^6 + 9*x^7 + 2*x^8 - 6*x^9 - 2*x^10). - Colin Barker, Jun 03 2018
EXAMPLE
Some solutions for n=5:
1 1 1 0 1 1 1 1 1 0 1 1 0 0 0 1 1 1 1 1 0
1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 0 1 1 1 1
0 0 0 1 1 1 1 0 0 1 0 1 1 1 1 1 0 1 1 0 1
0 0 0 1 1 0 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1
0 0 0 0 0 0 1 1 1 0 1 1 0 1 1 1 1 1 0 0 0
CROSSREFS
Cf. A202979.
Sequence in context: A255271 A293798 A027075 * A034331 A107278 A006762
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 26 2011
STATUS
approved