A252178 Number of length 2+2 0..n arrays with the sum of the maximum minus the minimum of adjacent triples multiplied by some arrangement of +-1 equal to zero.

12, 49, 132, 285, 536, 917, 1464, 2217, 3220, 4521, 6172, 8229, 10752, 13805, 17456, 21777, 26844, 32737, 39540, 47341, 56232, 66309, 77672, 90425, 104676, 120537, 138124, 157557, 178960, 202461, 228192, 256289, 286892, 320145, 356196, 395197

Offset

1,1

Links

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

Formula

Empirical: a(n) = (1/6)*n^4 + (7/3)*n^3 + (29/6)*n^2 + (11/3)*n + 1.

Conjectures from Colin Barker, Dec 01 2018: (Start)

G.f.: x*(12 - 11*x + 7*x^2 - 5*x^3 + x^4) / (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:
..4....2....0....4....2....6....2....1....4....1....4....4....2....4....2....2
..6....2....2....5....2....6....2....1....3....1....5....1....6....3....4....0
..0....0....3....1....1....0....4....6....2....2....0....6....0....4....2....6
..5....2....0....2....1....5....4....5....1....2....2....5....3....4....3....0

Crossrefs

Row 2 of A252177.

Sequence in context: A022282 A009959 A009950 * A218832 A307921 A288516

Adjacent sequences: A252175 A252176 A252177 * A252179 A252180 A252181

Keyword

nonn

Author

R. H. Hardin, Dec 15 2014

Status

approved