OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) + 16*a(n-2) - 16*a(n-3) - 41*a(n-4) + 16*a(n-5) + 16*a(n-6) - 4*a(n-7) - a(n-8).
Empirical g.f.: x*(8 + 7*x - 39*x^2 - 28*x^3 + 28*x^4 + 12*x^5 - 5*x^6 - x^7) / ((1 + x - x^2)*(1 - x - x^2)*(1 - 4*x - 13*x^2 + 4*x^3 + x^4)). - Colin Barker, Jan 04 2019
EXAMPLE
Some solutions for n=4:
..1..0..2..4..3....0..1.10..2..3....1..0..2..3..4....0..2..1..3..4
..6..5..8..7..9....6..5..7..9..8....6..5..7..8..9....6..5..7..9..8
.11.10.13.12.14...11.12..4.14.13...11.10.12.13.14...10.11.12.13.14
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 03 2015
STATUS
approved