A195520 - OEIS

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A195520

Number of lower triangles of an nXn -6..6 array with all row and column sums zero

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: A076481 A185834 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 23 01:22 EDT 2013. Contains 225585 sequences.