A140989 Half the number of n X n binary matrices, symmetric about both diagonal and antidiagonal, having equal row sums.

1, 2, 3, 12, 19, 173, 447, 8068, 36753, 1320227, 10915053, 783176689, 11979427593, 1712476502823, 48833478632641, 13961837241242892, 750837577374124089

Offset

1,2

Links

Table of n, a(n) for n=1..17.

Crossrefs

Sequence in context: A100570 A056700 A299547 * A281086 A355847 A374647

Adjacent sequences: A140986 A140987 A140988 * A140990 A140991 A140992

Keyword

nonn

Author

R. H. Hardin, Jul 28 2008

Status

approved