A351157 Number of symmetric 0-1 matrices with zero main diagonal where rows are sorted lexicographically and row sums are nondecreasing.

1, 2, 4, 11, 33, 145, 839, 7449

Offset

1,2

Links

Table of n, a(n) for n=1..8.

Crossrefs

Cf. A016121

Sequence in context: A123416 A123406 A123453 * A123459 A123426 A277204

Adjacent sequences: A351154 A351155 A351156 * A351158 A351159 A351160

Keyword

nonn,hard,more

Author

Max Alekseyev, Feb 02 2022

Status

approved