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A233402 Number of (n+1) X (1+1) 0..2 arrays with row and column sums nondecreasing, and no adjacent elements equal. 1
9, 11, 22, 24, 41, 42, 66, 65, 97, 93, 134, 126, 177, 164, 226, 207, 281, 255, 342, 308, 409, 366, 482, 429, 561, 497, 646, 570, 737, 648, 834, 731, 937, 819, 1046, 912, 1161, 1010, 1282, 1113, 1409, 1221, 1542, 1334, 1681, 1452, 1826, 1575, 1977, 1703, 2134 (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) = 3*a(n-2) - 3*a(n-4) + a(n-6).

Conjectures from Colin Barker, Oct 11 2018: (Start)

G.f.: x*(9 + 11*x - 5*x^2 - 9*x^3 + 2*x^4 + 3*x^5) / ((1 - x)^3*(1 + x)^3).

a(n) = (62 - 14*(-1)^n + (50-6*(-1)^n)*n + (11+(-1)^(1+n))*n^2) / 16.

(End)

EXAMPLE

Some solutions for n=5:

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

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

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

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

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

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

CROSSREFS

Column 1 of A233408.

Sequence in context: A022323 A106525 A103510 * A276406 A130730 A153697

Adjacent sequences: A233399 A233400 A233401 * A233403 A233404 A233405

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 09 2013

STATUS

approved

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Last modified February 7 16:06 EST 2023. Contains 360128 sequences. (Running on oeis4.)