A249846 - OEIS

A249846

Number of length 2+4 0..n arrays with no five consecutive terms having the maximum of any two terms equal to the minimum of the remaining three terms.

10, 198, 1500, 6916, 23526, 65226, 156184, 335016, 659682, 1213102, 2109492, 3501420, 5587582, 8621298, 12919728, 18873808, 26958906, 37746198, 51914764, 70264404, 93729174, 123391642, 160497864, 206473080, 262938130, 331726590

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OFFSET

1,1

COMMENTS

Row 2 of A249844.

LINKS

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

FORMULA

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

Conjectures from Colin Barker, Aug 18 2017: (Start)

G.f.: 2*x*(5 + 64*x + 162*x^2 + 112*x^3 + 17*x^4) / (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....5....1....0....5....0....1....6....5....3....6....5....0....5....1....5

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

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

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

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

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

CROSSREFS

Sequence in context: A224298 A222499 A097127 * A211419 A001085 A079436

Adjacent sequences: A249843 A249844 A249845 * A249847 A249848 A249849

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 07 2014

STATUS

approved