OFFSET
1,1
COMMENTS
Row 6 of A194998.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = 61488*n - 169100 for n>8.
Empirical g.f.: 2*x*(1 + 2302*x + 10914*x^2 + 11769*x^3 + 3985*x^4 + 1545*x^5 + 152*x^6 + 73*x^7 + 2*x^8 + x^9) / (1 - x)^2. - Colin Barker, May 06 2018
EXAMPLE
Some solutions for n=4:
..4............2............2............4............2............0
..3.4..........3.2..........1.0..........3.4..........3.4..........1.2
..2.3.2........4.3.2........0.1.0........2.3.4........4.3.2........2.3.4
..1.2.3.2......3.2.3.4......1.2.1.2......3.4.3.4......3.4.3.2......1.2.3.2
..0.1.2.3.2....2.3.4.3.2....0.1.0.1.2....2.3.2.3.2....2.3.2.1.2....2.1.2.1.2
..1.2.1.2.1.0..3.4.3.4.3.2..1.2.1.2.1.2..3.2.3.2.3.2..3.2.3.2.1.0..3.2.3.2.1.2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 07 2011
STATUS
approved