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A266543 Number of n X 4 binary arrays with rows and columns lexicographically nondecreasing and row and column sums nonincreasing. 1
2, 4, 6, 12, 16, 27, 36, 57, 76, 114, 149, 213, 276, 379, 485, 645, 811, 1051, 1304, 1652, 2021, 2511, 3034, 3709, 4431, 5338, 6311, 7510, 8795, 10352, 12020, 14010, 16142, 18653, 21340, 24469, 27813, 31669, 35786, 40492, 45507, 51196, 57252, 64073, 71324 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..179

FORMULA

Empirical: a(n) = a(n-1) + 2*a(n-2) - a(n-3) - a(n-4) - a(n-5) - a(n-6) + 2*a(n-8) + 2*a(n-9) - a(n-11) - a(n-12) - a(n-13) - a(n-14) + 2*a(n-15) + a(n-16) - a(n-17).

Empirical g.f.: x*(2 + 2*x - 2*x^2 - 2*x^4 - x^5 + x^6 + 5*x^7 + 4*x^8 + 3*x^9 - x^10 - 2*x^11 - 2*x^12 - x^13 + 4*x^14 + 2*x^15 - 2*x^16) / ((1 - x)^6*(1 + x)^3*(1 + x^2)*(1 + x + x^2)*(1 + x + x^2 + x^3 + x^4)). - Colin Barker, Jan 10 2019

EXAMPLE

Some solutions for n=6:

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

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

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

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

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

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

CROSSREFS

Column 4 of A266547.

Sequence in context: A007416 A293132 A098895 * A330711 A220219 A284456

Adjacent sequences:  A266540 A266541 A266542 * A266544 A266545 A266546

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 31 2015

STATUS

approved

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Last modified April 5 23:02 EDT 2020. Contains 333260 sequences. (Running on oeis4.)