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A229425 Number of n X 5 0..2 arrays with horizontal differences mod 3 never 1, vertical differences mod 3 never -1, rows lexicographically nondecreasing, and columns lexicographically nonincreasing. 2
17, 102, 524, 2204, 7816, 24126, 66503, 166972, 387738, 842802, 1731129, 3385828, 6344979, 11451106, 19987862, 33864276, 55858927, 89938670, 141669058, 218736396, 331604442, 494332150, 725582545, 1049856844, 1498992304 (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) = (1/259200)*n^10 + (1/6480)*n^9 + (149/60480)*n^8 + (163/7560)*n^7 + (10411/86400)*n^6 + (1063/2160)*n^5 + (19597/12960)*n^4 + (4169/1620)*n^3 + (30649/6300)*n^2 + (215/63)*n + 4.

Conjectures from Colin Barker, Sep 15 2018: (Start)

G.f.: x*(17 - 85*x + 337*x^2 - 755*x^3 + 1172*x^4 - 1284*x^5 + 987*x^6 - 525*x^7 + 186*x^8 - 40*x^9 + 4*x^10) / (1 - x)^11.

a(n) = 11*a(n-1) - 55*a(n-2) + 165*a(n-3) - 330*a(n-4) + 462*a(n-5) - 462*a(n-6) + 330*a(n-7) - 165*a(n-8) + 55*a(n-9) - 11*a(n-10) + a(n-11) for n>11.

(End)

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 5 of A229428.

Sequence in context: A234693 A022677 A275919 * A041552 A160767 A078625

Adjacent sequences:  A229422 A229423 A229424 * A229426 A229427 A229428

KEYWORD

nonn

AUTHOR

R. H. Hardin, Sep 22 2013

STATUS

approved

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Last modified July 27 08:33 EDT 2021. Contains 346304 sequences. (Running on oeis4.)