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A252869 Number of n X n nonnegative integer arrays with upper left 0 and lower right 2n-4 and value increasing by 0 or 1 with every step right or down. 2
0, 1, 44, 615, 7313, 85801, 1030330, 12742873, 161937617, 2105918045, 27918122131, 376111502977, 5136280530303, 70961632168027, 990271171218092, 13940676224604419, 197768060575469207, 2824828302263709187, 40595088350375470407, 586585037283553891311 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..20.

EXAMPLE

Some solutions for n=3

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

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

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

CROSSREFS

Main diagonal of A252876.

Column d=2 of A323849.

Sequence in context: A297680 A264680 A289647 * A296649 A221505 A160066

Adjacent sequences:  A252866 A252867 A252868 * A252870 A252871 A252872

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 24 2014

EXTENSIONS

a(16)-a(20) from Alois P. Heinz, Feb 07 2019

STATUS

approved

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Last modified January 18 19:40 EST 2020. Contains 331029 sequences. (Running on oeis4.)