OFFSET
3,3
LINKS
R. H. Hardin, Table of n, a(n) for n=3..99
FORMULA
Empirical: a(n) = 2*a(n-1)-a(n-2)+2*a(n-3)+2*a(n-4)-4*a(n-5); G.f.: -(-x-2*x^2-2*x^3+4*x^4)*x^3 / (1-2*x+x^2-2*x^3-2*x^4+4*x^5).
EXAMPLE
All solutions for 5 X 3:
.1.1.1...1.1.1...1.2.1...1.2.1
.2.2.2...2.3.2...1.3.1...1.2.1
.3.3.3...2.3.2...2.3.2...3.3.3
.1.2.1...1.3.1...2.3.2...2.2.2
.1.2.1...1.2.1...1.1.1...1.1.1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, formula from Alois P. Heinz in the Sequence Fans Mailing List, Jul 28 2010
STATUS
approved