A140722 Number of n X n symmetric matrices with nonnegative integer entries with each row sum i equal to i (1..n).

1, 2, 8, 61, 957, 31520, 2199080, 328002710, 105370907181

Offset

1,2

Links

Table of n, a(n) for n=1..9.

Crossrefs

Sequence in context: A005215 A058862 A191482 * A327078 A332779 A116976

Adjacent sequences: A140719 A140720 A140721 * A140723 A140724 A140725

Keyword

nonn

Author

R. H. Hardin, Jul 12 2008

Status

approved