OFFSET
1,1
COMMENTS
Column 1 of A223432.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 14*a(n-2) - 49*a(n-4) + 49*a(n-6) for n>7.
Empirical g.f.: x*(15 + 40*x - 90*x^2 - 204*x^3 + 143*x^4 + 252*x^5 - 35*x^6) / ((1 - 7*x^2 + 7*x^3)*(1 - 7*x^2 - 7*x^3)). - Colin Barker, Aug 20 2018
EXAMPLE
Some solutions for n=3:
..5....1....8....3....2....2...10....6....4....7....2....7....0....2....4....8
..8....4....5....7....5....4....6....3....8....3....0....3....2....4....2....5
.13....2....8...12....2....2....3....6....5....1....2....7....4....8....4....9
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 20 2013
STATUS
approved