OFFSET
1,1
COMMENTS
Column 7 of A189326.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = 140*n - 751 for n>8.
Empirical g.f.: x*(11 - 5*x + 8*x^2 + 6*x^3 + 20*x^4 + 26*x^5 + 30*x^6 + 25*x^7 + 14*x^8 + 5*x^9) / (1 - x)^2. - Colin Barker, May 02 2018
EXAMPLE
Some solutions for n=3:
..1....7....2....2....1....3....3....1....1....3....1....1....1....4....1....1
..4....7....5....5....3....4....4....3....3....7....6....3....5....7....2....5
..5....7....5....5....4....7....4....4....3....7....7....4....6....7....3....6
..6....7....5....7....7....7....7....5....4....7....7....4....6....7....5....7
..7....7....7....7....7....7....7....7....7....7....7....7....7....7....7....7
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 20 2011
STATUS
approved