A249713 Number of length 7+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.

72, 1177, 7056, 27113, 80360, 200489, 442144, 888465, 1659976, 2924889, 4910896, 7918521, 12336104, 18656489, 27495488, 39612193, 55931208, 77566873, 105849552, 142354057, 188930280, 247736105, 321272672, 412422065, 524487496, 661236057

Offset

1,1

Links

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

Formula

Empirical: a(n) = (1/70)*n^7 + (19/15)*n^6 + (178/15)*n^5 + 30*n^4 + (851/30)*n^3 + (56/15)*n^2 - (446/105)*n + 1.

Conjectures from Colin Barker, Nov 10 2018: (Start)

G.f.: x*(72 + 601*x - 344*x^2 - 411*x^3 + 152*x^4 - 5*x^5 + 8*x^6 - x^7) / (1 - x)^8.

a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>8.

(End)

Example

Some solutions for n=5:
..5....4....1....3....1....3....5....1....1....4....3....5....2....2....3....3
..0....0....2....3....5....1....0....3....3....4....3....0....2....4....1....0
..1....4....1....3....1....0....3....1....1....4....3....4....4....4....2....1
..1....5....1....3....1....1....3....1....1....4....3....4....2....4....2....1
..1....4....0....3....0....2....3....1....1....4....0....4....2....2....3....2
..1....3....3....3....1....1....4....1....0....1....4....0....2....4....2....1
..0....4....1....3....4....1....1....0....1....4....3....4....2....4....2....1
..1....5....1....3....1....0....3....4....3....4....3....4....2....5....2....1
..3....4....1....4....0....3....3....1....1....5....1....5....1....4....2....5
..1....2....4....3....1....1....4....1....0....2....3....3....4....0....4....0

Crossrefs

Row 7 of A249707.

Sequence in context: A064567 A269088 A168194 * A269074 A200556 A239423

Adjacent sequences: A249710 A249711 A249712 * A249714 A249715 A249716

Keyword

nonn

Author

R. H. Hardin, Nov 04 2014

Status

approved