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URL: https://oeis.org/A322487

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A322487
Number of (3*n) X n matrices with nonnegative integer entries and each column sum being 3 up to permutation of rows.
6
1, 3, 31, 686, 27036, 1688360, 154703688, 19692332568, 3342458334775, 732812082630803, 202322386045180686, 68898094282978653925, 28443422251718020038049, 14029033632468285836567998, 8164217197799501761637725983, 5545466507405459243366712102466
OFFSET
0,2
COMMENTS
Also number of multiset partitions of [1,1,1,2,2,2,...,n,n,n] into nonempty multisets. - Marko Riedel, Nov 29 2022
LINKS
EXAMPLE
a(1) = 3 because up to permutations of rows there are 3 column vectors with sum 3: [1, 1, 1], [2, 1, 0] and [3, 0, 0].
CROSSREFS
Row n=3 of A219727.
Sequence in context: A380513 A104841 A092552 * A300735 A196457 A136370
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Dec 11 2018
STATUS
approved