OFFSET
1,1
COMMENTS
Column 5 of A183362.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = 2*a(n-1) + 2*a(n-3) + a(n-4) for n>7.
Empirical g.f.: 36*x*(3 + 58*x - 20*x^2 + 34*x^3 + 29*x^4 - 24*x^5 - 12*x^6) / ((1 + x^2)*(1 - 2*x - x^2)). - Colin Barker, Mar 28 2018
EXAMPLE
Some solutions for 7 X 5 with a(1,1)=1:
..1..1..2..4..1....1..2..2..3..3....1..2..2..3..3....1..1..3..4..1
..4..3..3..4..2....1..4..4..1..2....3..4..4..1..1....4..2..2..4..3
..2..2..1..1..3....2..3..3..1..2....2..1..3..2..2....3..3..1..1..2
..3..4..4..2..3....4..1..2..4..4....2..1..3..4..4....2..4..4..3..2
..1..1..3..2..1....3..1..2..3..3....3..4..2..1..1....1..1..2..3..1
..4..2..3..4..4....2..4..4..1..2....3..4..2..3..3....4..3..2..4..1
..3..2..1..1..2....2..3..3..1..4....2..1..1..4..2....2..3..1..4..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 04 2011
STATUS
approved