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A195520 Number of lower triangles of an n X n -6..6 array with all row and column sums zero 0
1, 1, 13, 1105, 1089411, 11131321791, 1252997799222737, 1582560262323178069903 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Column 6 of A195522

LINKS

Table of n, a(n) for n=1..8.

EXAMPLE

Some solutions for n=4

..0........0........0........0........0........0........0........0

..0.0......0.0......0.0.....-3.3.....-5.5.....-2.2......5-5.....-5.5

..4.0-4...-4.4.0....3-2-1...-3.3.0...-1-3.4....4.0-4...-6.4.2....3-4.1

.-4.0.4.0..4-4.0.0.-3.2.1.0..6-6.0.0..6-2-4.0.-2-2.4.0..1.1-2.0..2-1-1.0

CROSSREFS

Sequence in context: A185834 A264249 A195890 * A128897 A201265 A221390

Adjacent sequences:  A195517 A195518 A195519 * A195521 A195522 A195523

KEYWORD

nonn

AUTHOR

R. H. Hardin Sep 20 2011

STATUS

approved

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Last modified May 18 16:24 EDT 2022. Contains 353816 sequences. (Running on oeis4.)