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A351158
Number of n X n symmetric 0-1 matrices where rows are sorted lexicographically and row sums are nondecreasing.
2
2, 5, 15, 56, 275, 1897, 18948
OFFSET
1,1
CROSSREFS
Sequence in context: A121392 A216388 A005976 * A187981 A334155 A373768
KEYWORD
nonn,hard,more
AUTHOR
Max Alekseyev, Feb 02 2022
STATUS
approved