OFFSET
1,3
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 18*a(n-1) - 91*a(n-2) + 469*a(n-3) - 919*a(n-4) + 2152*a(n-5) - 93*a(n-6) + a(n-7).
Empirical g.f.: 2*x^3*(1 - x)*(4 - 9*x + 46*x^2 - x^3) / (1 - 18*x + 91*x^2 - 469*x^3 + 919*x^4 - 2152*x^5 + 93*x^6 - x^7). - Colin Barker, Sep 22 2018
EXAMPLE
Some solutions for n=3:
..0..1..0..7....0..1..4..5....0..1..2..1....0..1..2..3....0..1..2..3
..2..3..6..5....2..3..6..7....0..3..0..7....0..1..4..5....0..7..4..3
..4..5..4..3....2..1..0..7....4..5..6..5....0..7..6..5....6..5..4..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 01 2013
STATUS
approved