OFFSET
1,2
COMMENTS
Column 6 of A181196.
LINKS
R. H. Hardin, Table of n, a(n) for n=1..100
FORMULA
Empirical: a(n) = 120*a(n-1) - 1672*a(n-2) + 544*a(n-3) - 6672*a(n-4) + 256*a(n-5).
Empirical g.f.: x*(1 - 78*x + 164*x^2 - 1976*x^3 + 224*x^4) / ((1 - 16*x)*(1 - 104*x + 4*x^2)*(1 + 4*x^2)). - Colin Barker, Feb 27 2018
EXAMPLE
Some solutions for 4 X 6:
..1..2..3..4..5..6....1..2..3..4..5..6....1..2..3..4..5..6....1..2..3..4..5..6
..7..8..9.10.11.12....7..8..9.10.11.12....7..8..9.10.11.12....7..8..9.10.11.12
.13.14.15.16.17.18...13.14.15.17.19.20...13.14.15.17.19.21...13.14.15.17.19.22
.19.20.21.22.23.24...16.18.21.22.23.24...16.18.20.22.23.24...16.18.20.21.23.24
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 10 2010
STATUS
approved