A351158 Number of n X n symmetric 0-1 matrices where rows are sorted lexicographically and row sums are nondecreasing.

2, 5, 15, 56, 275, 1897, 18948

Offset

1,1

Links

Table of n, a(n) for n=1..7.

Crossrefs

Sequence in context: A121392 A216388 A005976 * A187981 A334155 A348365

Adjacent sequences: A351155 A351156 A351157 * A351159 A351160 A351161

Keyword

nonn,hard,more

Author

Max Alekseyev, Feb 02 2022

Status

approved