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A331647
Number of nonnegative integer matrices with 3 columns and any number of distinct nonzero rows with column sums n.
2
1, 13, 313, 11655, 439779, 14699033, 453027131, 14035890205, 418049781331, 11878976385087, 326859368114097, 8708114475309677, 224507928640721933, 5621130329235752857, 136998397230581620801, 3253556714665728184671, 75415948071516657175683, 1708706073099458659898237
OFFSET
0,2
EXAMPLE
The a(1) = 13 matrices are:
[1 0 0] [1 0 0] [0 1 0] [0 1 0] [0 0 1] [0 0 1]
[0 1 0] [0 0 1] [1 0 0] [0 0 1] [1 0 0] [0 1 0]
[0 0 1] [0 1 0] [0 0 1] [1 0 0] [0 1 0] [1 0 0]
.
[1 1 0] [1 0 1] [1 0 0] [0 1 1] [0 1 0] [0 0 1] [1 1 1]
[0 0 1] [0 1 0] [0 1 1] [1 0 0] [1 0 1] [1 1 0]
CROSSREFS
Column k=3 of A331568.
Cf. A331646.
Sequence in context: A217674 A360324 A241022 * A331644 A052114 A305143
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Jan 23 2020
STATUS
approved