A250338 Number of length 2+5 0..n arrays with every six consecutive terms having the maximum of some three terms equal to the minimum of the remaining three terms.

68, 907, 5264, 20085, 59396, 147903, 325312, 651369, 1211620, 2123891, 3545488, 5681117, 8791524, 13202855, 19316736, 27621073, 38701572, 53253979, 72097040, 96186181, 126627908, 164694927, 211841984, 269722425, 340205476, 425394243

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = n^6 + 9*n^5 + 20*n^4 + (68/3)*n^3 + 12*n^2 + (7/3)*n + 1.

Conjectures from Colin Barker, Nov 12 2018: (Start)

G.f.: x*(68 + 431*x + 343*x^2 - 96*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:
..2....0....3....0....4....4....3....3....0....2....2....2....3....0....0....3
..1....0....4....6....5....0....5....5....2....2....2....2....4....5....0....5
..3....2....5....2....5....2....6....2....2....0....1....4....3....5....6....3
..3....2....6....3....5....2....6....0....3....1....2....3....4....2....0....5
..4....5....4....2....3....2....3....2....4....5....5....3....6....2....0....5
..3....6....1....0....5....4....5....2....2....2....1....3....6....0....0....5
..5....1....4....2....0....4....0....0....1....5....5....6....1....2....4....4

Crossrefs

Row 2 of A250336.

Sequence in context: A200876 A039507 A250144 * A223374 A360656 A254645

Adjacent sequences: A250335 A250336 A250337 * A250339 A250340 A250341

Keyword

nonn

Author

R. H. Hardin, Nov 19 2014

Status

approved