login
A249712
Number of length 6+3 0..n arrays with every four consecutive terms having the maximum of some two terms equal to the minimum of the remaining two terms.
1
52, 659, 3440, 11925, 32500, 75495, 156416, 297321, 528340, 889339, 1431728, 2220413, 3335892, 4876495, 6960768, 9730001, 13350900, 18018403, 23958640, 31432037, 40736564, 52211127, 66239104, 83252025, 103733396, 128222667
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = (1/5)*n^6 + (73/15)*n^5 + 18*n^4 + 22*n^3 + (34/5)*n^2 - (13/15)*n + 1.
Conjectures from Colin Barker, Nov 10 2018: (Start)
G.f.: x*(52 + 295*x - 81*x^2 - 136*x^3 + 20*x^4 - 7*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=6:
..4....2....3....2....4....2....4....5....3....0....5....0....3....5....6....6
..3....6....3....0....5....5....2....4....0....3....6....5....3....4....2....5
..6....4....1....2....3....2....2....4....2....3....5....5....3....6....3....2
..4....4....5....6....4....1....0....1....2....6....5....5....3....5....3....5
..4....0....3....2....4....2....2....4....2....3....4....5....2....5....3....5
..1....4....3....2....4....6....2....4....5....3....5....5....3....5....3....5
..4....4....3....0....5....2....2....4....1....2....5....5....3....5....5....6
..4....4....1....5....4....1....2....5....2....4....6....6....4....2....3....5
..6....4....5....2....2....2....2....3....2....3....2....5....3....5....3....1
CROSSREFS
Row 6 of A249707.
Sequence in context: A100413 A221272 A254137 * A255945 A215365 A339142
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 04 2014
STATUS
approved