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A266430 Number of 4 X n binary arrays with rows and columns lexicographically nondecreasing and column sums nondecreasing. 1
5, 22, 96, 404, 1556, 5365, 16585, 46463, 119452, 285124, 638247, 1351194, 2724385, 5262379, 9785590, 17590461, 30674359, 52045522, 86143170, 139398464, 220973442, 343722465, 525429159, 790381435, 1171358006, 1712112000, 2470450897 (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) = (1/9979200)*n^11 + (1/201600)*n^10 + (1/12096)*n^9 + (1/1344)*n^8 + (1271/302400)*n^7 + (479/28800)*n^6 + (12797/181440)*n^5 + (97/504)*n^4 + (1779/2800)*n^3 + (2032/1575)*n^2 + (8269/4620)*n + 1.

Conjectures from Colin Barker, Jan 09 2019: (Start)

G.f.: x*(5 - 38*x + 162*x^2 - 396*x^3 + 679*x^4 - 833*x^5 + 737*x^6 - 471*x^7 + 213*x^8 - 65*x^9 + 12*x^10 - x^11) / (1 - x)^12.

a(n) = 12*a(n-1) - 66*a(n-2) + 220*a(n-3) - 495*a(n-4) + 792*a(n-5) - 924*a(n-6) + 792*a(n-7) - 495*a(n-8) + 220*a(n-9) - 66*a(n-10) + 12*a(n-11) - a(n-12) for n>12.

(End)

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Row 4 of A266428.

Sequence in context: A116415 A026861 A026888 * A083586 A200676 A297333

Adjacent sequences:  A266427 A266428 A266429 * A266431 A266432 A266433

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 29 2015

STATUS

approved

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Last modified September 28 21:53 EDT 2020. Contains 337414 sequences. (Running on oeis4.)