A266357 - OEIS

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A266357

Number of n X 3 binary arrays with rows and columns lexicographically nondecreasing and row and column sums nondecreasing.

4, 13, 35, 82, 173, 337, 614, 1060, 1749, 2777, 4266, 6369, 9273, 13206, 18441, 25302, 34170, 45490, 59776, 77620, 99698, 126778, 159728, 199525, 247262, 304159, 371571, 450998, 544095, 652683, 778758, 924504, 1092303, 1284747, 1504650, 1755061

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

Empirical: a(n) = 5*a(n-1) -9*a(n-2) +6*a(n-3) -6*a(n-7) +9*a(n-8) -5*a(n-9) +a(n-10).

Empirical g.f.: x*(4 - 7*x + 6*x^2 - 6*x^6 + 9*x^7 - 5*x^8 + x^9) / ((1 - x)^7*(1 + x)*(1 + x + x^2)). - Colin Barker, Jan 09 2019

EXAMPLE

Some solutions for n=4:

..0..0..1....0..0..0....0..0..1....0..0..1....0..0..1....0..0..0....0..0..0

..0..0..1....0..0..1....0..1..1....0..1..0....0..1..1....0..0..1....0..0..0

..0..1..0....0..1..1....1..1..1....0..1..0....1..0..1....0..0..1....0..1..1

..1..0..1....1..1..0....1..1..1....1..0..1....1..1..1....0..1..1....1..1..1

CROSSREFS

Column 3 of A266362.

Sequence in context: A089453 A057159 A189588 * A095941 A210843 A177155

Adjacent sequences: A266354 A266355 A266356 * A266358 A266359 A266360

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 28 2015

STATUS

approved