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A333681
Number of non-isomorphic n X n binary matrices with all row and column sums equal up to permutation of rows and columns.
3
1, 2, 3, 4, 6, 8, 19, 44, 314, 7526, 846993, 324127860, 403254094632, 1555631972009430, 19731915624463099553, 791773335030637885025288, 107432353216118868234728540268, 47049030539260648478475949282317452, 71364337698829887974206671525372672234855
OFFSET
0,2
FORMULA
a(n) = A000519(n) + 1.
EXAMPLE
The a(2) = 3 matrices are:
[0 0] [0 1] [1 1]
[0 0] [1 0] [1 1]
CROSSREFS
Row sums of A133687.
Sequence in context: A008324 A333732 A274456 * A084074 A144722 A105808
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Apr 01 2020
STATUS
approved