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A249708 Number of length 2+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
14, 69, 208, 485, 966, 1729, 2864, 4473, 6670, 9581, 13344, 18109, 24038, 31305, 40096, 50609, 63054, 77653, 94640, 114261, 136774, 162449, 191568, 224425, 261326, 302589, 348544, 399533, 455910, 518041, 586304, 661089, 742798, 831845, 928656 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = (1/2)*n^4 + 4*n^3 + (11/2)*n^2 + 3*n + 1.

Conjectures from Colin Barker, Nov 09 2018: (Start)

G.f.: x*(2 - x)*(7 + 3*x + 3*x^2 - x^3) / (1 - x)^5.

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5.

(End)

EXAMPLE

Some solutions for n=6:

..3....6....0....3....0....0....2....3....3....5....5....3....4....4....0....2

..2....2....2....4....4....4....1....2....1....6....3....5....1....0....4....2

..0....2....3....4....4....5....0....2....5....5....4....6....2....4....1....2

..2....0....2....6....5....4....1....2....3....5....4....5....2....4....1....2

..4....6....0....3....1....2....2....5....3....4....5....5....2....6....0....1

CROSSREFS

Row 2 of A249707.

Sequence in context: A254004 A238822 A244943 * A008354 A051879 A236157

Adjacent sequences:  A249705 A249706 A249707 * A249709 A249710 A249711

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 04 2014

STATUS

approved

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Last modified November 21 12:11 EST 2019. Contains 329370 sequences. (Running on oeis4.)