OFFSET
1,2
COMMENTS
Column 7 of A215870.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 61*a(n-2) -99*a(n-4) -2*a(n-6).
Empirical: g.f.: -x*(-1 -5*x +32*x^2 +43*x^3 +28*x^4 +2*x^5) / ( 1 -61*x^2 +99*x^4 +2*x^6 ). - R. J. Mathar, Nov 27 2015
EXAMPLE
Some solutions for n=4:
..x..0..x..2..x..4..x....x..0..x..2..x..4..x....x..0..x..2..x..4..x
..1..x..3..x..5..x..7....1..x..3..x..5..x..8....1..x..3..x..6..x..8
..x..6..x..9..x.10..x....x..6..x..9..x.10..x....x..5..x..7..x.10..x
..8..x.11..x.12..x.13....7..x.11..x.12..x.13....9..x.11..x.12..x.13
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 25 2012
STATUS
approved