OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (1/39916800)*n^11 + (1/907200)*n^10 + (17/725760)*n^9 + (19/60480)*n^8 + (3691/1209600)*n^7 + (1003/43200)*n^6 + (21115/145152)*n^5 + (106243/181440)*n^4 + (1170209/907200)*n^3 + (35051/25200)*n^2 + (7783/13860)*n.
Empirical g.f.: x*(4 - 15*x + 26*x^2 - 19*x^3 + x^4 + 8*x^5 - 5*x^6 + x^7) / (1 - x)^12. - Colin Barker, Feb 10 2019
EXAMPLE
Some solutions for n=4:
..0..0..0. .1..1..0. .1..1..0. .1..1..0. .1..0..0. .1..1..1. .1..0..0
..1..1..1. .1..1..0. .1..1..1. .0..0..0. .1..1..0. .1..1..1. .1..1..0
..0..0..0. .0..0..1. .1..0..1. .1..0..1. .0..1..1. .1..1..1. .0..1..0
..1..1..1. .1..0..1. .1..0..1. .1..1..1. .1..0..1. .1..1..0. .0..1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 25 2016
STATUS
approved