OFFSET
1,1
COMMENTS
Row 5 of A194998.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = 2952*n - 6910 for n>6.
Empirical g.f.: 2*x*(1 + 286*x + 570*x^2 + 493*x^3 + 84*x^4 + 39*x^5 + 2*x^6 + x^7) / (1 - x)^2. - Colin Barker, May 06 2018
EXAMPLE
Some solutions for n=4:
..0..........0..........1..........0..........0..........4..........1
..1.2........1.2........2.1........1.2........1.0........3.2........2.1
..2.1.0......2.1.2......1.2.3......2.1.2......2.1.0......2.3.2......1.2.3
..1.2.1.2....1.2.1.2....0.1.2.3....3.2.3.4....3.2.1.2....3.4.3.2....0.1.2.3
..0.1.2.3.4..2.1.0.1.0..1.2.3.2.3..2.3.2.3.2..2.3.2.1.0..4.3.2.1.0..1.2.3.4.3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 07 2011
STATUS
approved