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A252971 Number of nX3 nonnegative integer arrays with upper left 0 and lower right n+3-5 and value increasing by 0 or 1 with every step right or down. 1
0, 1, 18, 153, 770, 2859, 8694, 22924, 54272, 118057, 239798, 460207, 841930, 1478451, 2505634, 4116442, 6579440, 10261761, 15657290, 23420901, 34409666, 49732043, 70806142, 99428264, 137853008, 188886345, 255993166, 343420923 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Column 3 of A252976.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = (1/90720)*n^9 + (1/2520)*n^8 + (19/3780)*n^7 + (7/360)*n^6 - (59/4320)*n^5 - (19/180)*n^4 + (5827/45360)*n^3 - (32/35)*n^2 + (3629/1260)*n - 2.

Empirical: G.f.: x^2*(1+8*x+18*x^2-70*x^3+94*x^4-78*x^5+43*x^6-14*x^7+2*x^8) / (x-1)^10. - R. J. Mathar, Nov 23 2015

EXAMPLE

Some solutions for n=4

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

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

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

..2..2..2....1..2..2....1..1..2....1..2..2....1..2..2....1..1..2....2..2..2

CROSSREFS

Sequence in context: A294486 A228994 A235397 * A047643 A010934 A022613

Adjacent sequences:  A252968 A252969 A252970 * A252972 A252973 A252974

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 25 2014

STATUS

approved

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Last modified July 9 16:50 EDT 2020. Contains 335545 sequences. (Running on oeis4.)