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A252871 Number of nX3 nonnegative integer arrays with upper left 0 and lower right n+3-4 and value increasing by 0 or 1 with every step right or down 2
1, 8, 44, 153, 413, 949, 1948, 3676, 6497, 10894, 17492, 27083, 40653, 59411, 84820, 118630, 162913, 220100, 293020, 384941, 499613, 641313, 814892, 1025824, 1280257, 1585066, 1947908, 2377279, 2882573, 3474143, 4163364, 4962698, 5885761, 6947392 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 3 of A252876

LINKS

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

FORMULA

Empirical: a(n) = (1/360)*n^6 + (1/20)*n^5 + (5/18)*n^4 + (1/3)*n^3 + (79/360)*n^2 - (113/60)*n + 2.

Empirical: G.f.: -x*(1+x+9*x^2-22*x^3+21*x^4-10*x^5+2*x^6) / (x-1)^7. - R. J. Mathar, Nov 23 2015

EXAMPLE

Some solutions for n=3

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

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

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

CROSSREFS

Sequence in context: A261996 A036464 A000938 * A307044 A165618 A250285

Adjacent sequences:  A252868 A252869 A252870 * A252872 A252873 A252874

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 24 2014

STATUS

approved

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Last modified March 24 12:14 EDT 2019. Contains 321448 sequences. (Running on oeis4.)