OFFSET
1,2
COMMENTS
Equivalent to all 1s connected only in 2 X 2 blocks.
Column 5 of A183342.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = a(n-1) + a(n-2) + 5*a(n-3) + 2*a(n-4) + a(n-5) - a(n-7) - a(n-8).
Empirical g.f.: x*(1 + 5*x + 6*x^2 + 2*x^3 + x^4 - x^5 - 2*x^6 - x^7) / (1 - x - x^2 - 5*x^3 - 2*x^4 - x^5 + x^7 + x^8). - Colin Barker, Mar 27 2018
EXAMPLE
Some solutions for 7 X 5:
1 1 0 0 0 0 0 0 1 1 0 0 1 1 0 0 0 1 1 0
1 1 0 0 0 0 0 0 1 1 0 0 1 1 0 0 0 1 1 0
0 0 1 1 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0
0 0 1 1 0 0 0 0 0 0 1 1 0 0 0 1 1 0 1 1
0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 1 1 0 1 1
1 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0
1 1 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 04 2011
STATUS
approved