OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..178
FORMULA
Empirical: a(n) = (11/90)*n^6 + (11/5)*n^5 + (167/36)*n^4 - (43/6)*n^3 + (583/180)*n^2 - (61/30)*n + 1.
Conjectures from Colin Barker, Sep 14 2018: (Start)
G.f.: x*(2 + 91*x + 137*x^2 - 148*x^3 - 4*x^4 + 9*x^5 + x^6) / (1 - x)^7.
a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>7.
(End)
EXAMPLE
Some solutions for n=4:
..3....2....3....1....1....0....1....1....1....0....2....4....3....1....1....1
..3....2....3....3....1....1....1....0....2....1....4....2....0....3....2....1
..4....0....2....3....1....3....3....3....2....2....2....2....4....3....2....0
..1....4....3....3....1....3....0....3....2....2....4....1....2....3....1....1
..3....0....3....4....0....4....3....3....2....4....1....2....2....1....0....0
..0....1....3....0....2....2....3....1....0....3....3....1....1....3....1....4
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 10 2013
STATUS
approved