OFFSET
1,5
COMMENTS
Column 1 of A278372.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (1/39916800)*n^11 + (1/604800)*n^10 + (17/725760)*n^9 - (1/10080)*n^8 - (227/172800)*n^7 + (193/28800)*n^6 - (1273/725760)*n^5 - (1909/60480)*n^4 + (31169/907200)*n^3 + (629/25200)*n^2 - (31/990)*n.
Empirical g.f.: x^5*(2 - x)*(3 - 2*x)*(1 + 2*x - 2*x^2) / (1 - x)^12. - Colin Barker, Mar 22 2018
EXAMPLE
Some solutions for n=8:
..0. .2. .2. .1. .1. .0. .2. .2. .2. .2. .2. .0. .2. .2. .2. .2
..2. .0. .2. .0. .2. .2. .0. .0. .0. .0. .2. .1. .2. .0. .1. .0
..1. .0. .2. .2. .1. .1. .1. .1. .2. .1. .2. .0. .1. .0. .0. .2
..2. .1. .1. .0. .0. .0. .2. .0. .0. .0. .1. .2. .2. .1. .1. .2
..0. .0. .0. .2. .2. .2. .0. .1. .1. .1. .0. .0. .0. .0. .2. .1
..0. .2. .2. .1. .0. .0. .1. .1. .0. .2. .1. .2. .2. .1. .2. .1
..2. .1. .0. .2. .2. .0. .0. .0. .0. .2. .1. .1. .1. .1. .0. .0
..0. .1. .2. .2. .2. .1. .1. .1. .2. .0. .0. .2. .2. .0. .0. .2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 19 2016
STATUS
approved