A219853 - OEIS

A219853

Number of 2 X n arrays of the minimum value of corresponding elements and their horizontal or antidiagonal neighbors in a random, but sorted with lexicographically nondecreasing rows and nonincreasing columns, 0..2 2 X n array.

6, 7, 17, 33, 56, 86, 125, 173, 230, 296, 371, 455, 548, 650, 761, 881, 1010, 1148, 1295, 1451, 1616, 1790, 1973, 2165, 2366, 2576, 2795, 3023, 3260, 3506, 3761, 4025, 4298, 4580, 4871, 5171, 5480, 5798, 6125, 6461, 6806, 7160, 7523, 7895, 8276, 8666, 9065

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OFFSET

1,1

COMMENTS

Row 2 of A219852.

LINKS

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

FORMULA

Empirical: a(n) = (9/2)*n^2 - (39/2)*n + 41 for n>4.

Conjectures from Colin Barker, Jul 28 2018: (Start)

G.f.: x*(6 - 11*x + 14*x^2 - 3*x^3 + x^4 + 2*x^6) / (1 - x)^3.

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

(End)

EXAMPLE

Some solutions for n=3:

..0..0..0....1..0..0....2..1..1....1..1..1....1..1..1....2..0..0....0..0..0

..0..0..1....1..0..2....2..1..2....1..1..1....1..0..0....2..0..2....0..0..0

CROSSREFS

Cf. A219852.

Sequence in context: A315846 A062850 A139450 * A250196 A260563 A118666

Adjacent sequences: A219850 A219851 A219852 * A219854 A219855 A219856

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 29 2012

STATUS

approved