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A184546 Number of (n+2) X 9 binary arrays with each 3 X 3 subblock having rows and columns in lexicographically nondecreasing order. 1
539, 1513, 3461, 7307, 14767, 28844, 54543, 99872, 177207, 305112, 510719, 832788, 1325583, 2063717, 3148137, 4713439, 6936723, 10048219, 14343937, 20200617, 28093279, 38615698, 52504155, 70664842, 94205327, 124470514, 163083563 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 7 of A184548.
LINKS
FORMULA
Empirical: a(n) = (1/362880)*n^9 + (1/5760)*n^8 + (289/60480)*n^7 + (217/2880)*n^6 + (12949/17280)*n^5 + (28049/5760)*n^4 + (468401/22680)*n^3 + (210319/1440)*n^2 + (145955/504)*n + 77.
Conjectures from Colin Barker, Apr 14 2018: (Start)
G.f.: x*(539 - 3877*x + 12586*x^2 - 23898*x^3 + 29072*x^4 - 23429*x^5 + 12502*x^6 - 4270*x^7 + 853*x^8 - 77*x^9) / (1 - x)^10.
a(n) = 10*a(n-1) - 45*a(n-2) + 120*a(n-3) - 210*a(n-4) + 252*a(n-5) - 210*a(n-6) + 120*a(n-7) - 45*a(n-8) + 10*a(n-9) - a(n-10) for n>10.
(End)
EXAMPLE
Some solutions for 4 X 9:
..0..0..0..0..0..0..0..0..0....0..0..0..0..0..0..0..0..0
..0..0..0..0..0..0..0..0..0....0..0..0..0..0..0..0..1..1
..0..0..0..0..0..0..0..0..0....0..0..1..1..1..1..1..0..1
..1..1..1..1..1..1..1..1..1....0..0..1..1..1..1..1..1..0
CROSSREFS
Cf. A184548.
Sequence in context: A111258 A239347 A118630 * A252386 A289221 A345390
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 16 2011
STATUS
approved

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Last modified June 23 10:04 EDT 2024. Contains 373629 sequences. (Running on oeis4.)