A250391 Number of length 5+3 0..n arrays with no four consecutive terms having the maximum of any two terms equal to the minimum of the remaining two terms.

6, 514, 9480, 82398, 457366, 1886948, 6308960, 18038628, 45704886, 105193902, 223903240, 446650386, 843619686, 1520772064, 2633182208, 4401808232, 7134239142, 11250005754, 17311081032, 26058236134, 38453958774, 55732680828

Offset

1,1

Comments

Row 5 of A250387.

Links

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

Formula

Empirical: a(n) = n^8 + (1/5)*n^7 + (563/180)*n^6 + (19/30)*n^5 + (1/9)*n^4 + (9/5)*n^3 - (223/180)*n^2 + (11/30)*n.

Conjectures from Colin Barker, Aug 21 2017: (Start)

G.f.: 2*x*(3 + 230*x + 2535*x^2 + 7539*x^3 + 7322*x^4 + 2335*x^5 + 196*x^6) / (1 - x)^9.

a(n) = 9*a(n-1) - 36*a(n-2) + 84*a(n-3) - 126*a(n-4) + 126*a(n-5) - 84*a(n-6) + 36*a(n-7) - 9*a(n-8) + a(n-9) for n>9.

(End)

Example

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

Crossrefs

Sequence in context: A290937 A364482 A365926 * A003395 A222607 A000411

Adjacent sequences: A250388 A250389 A250390 * A250392 A250393 A250394

Keyword

nonn

Author

R. H. Hardin, Nov 20 2014

Status

approved