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A333740
Number of inequivalent 2n X 2n binary matrices with rows and columns summing to n, where equivalence means permutations of rows or columns.
2
1, 1, 2, 7, 194, 601055, 294494683312, 14584161564179926207, 80055722734531008786502722278, 53505113579082591021525466231199449015539
OFFSET
0,3
FORMULA
a(n) = A133687(2n,n).
CROSSREFS
Cf. A133687.
Sequence in context: A307582 A125610 A247028 * A306951 A181864 A096463
KEYWORD
nonn,more
AUTHOR
Alois P. Heinz, Apr 03 2020
STATUS
approved