A140422 Half the number of n X n symmetric binary matrices with every 1 adjacent to some 0 horizontally or vertically and every 0 adjacent to some 1 horizontally or vertically.

1, 5, 47, 849, 29241, 1901849, 234932757, 55047807551, 24470603864937, 20637055514911557, 33018065501295740951, 100220335496292824426843, 577112450349963078523926227

Offset

2,2

Links

Table of n, a(n) for n=2..14.

Crossrefs

Sequence in context: A247982 A222078 A061572 * A145564 A159480 A196460

Adjacent sequences: A140419 A140420 A140421 * A140423 A140424 A140425

Keyword

nonn

Author

R. H. Hardin, Jun 18 2008

Status

approved