OFFSET
1,1
COMMENTS
Row 4 of A211836.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (1/48)*n^6 + (19/48)*n^5 + (51/16)*n^4 + (661/48)*n^3 + (835/24)*n^2 + (317/6)*n + 41.
Conjectures from Colin Barker, Jul 20 2018: (Start)
G.f.: x*(146 - 561*x + 1093*x^2 - 1210*x^3 + 781*x^4 - 275*x^5 + 41*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=3:
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
..1....0....1....1....0....1....1....1....1....1....1....0....1....1....1....1
..2....1....2....2....1....2....2....1....0....2....1....1....0....2....2....2
..3....0....3....0....2....1....3....2....2....1....2....2....2....1....3....3
..4....2....0....3....0....0....4....3....3....2....2....3....3....0....2....4
..1....3....3....4....3....3....0....1....0....1....3....2....4....3....4....3
..0....3....0....4....4....4....5....4....1....3....4....3....4....4....1....5
..0....4....4....5....1....3....6....2....4....4....3....4....0....4....2....0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 21 2012
STATUS
approved