A145778 Number of n X n binary arrays symmetric about the diagonal and under 90-degree rotation with all ones connected only either two adjacent vertically or two adjacent horizontally.

1, 1, 1, 2, 2, 3, 6, 10, 21, 46, 106, 253, 820, 2128, 8527, 25843, 122734, 425169, 2572337, 9924088, 75407076, 331598798, 3087553649, 15467749658, 179756366268, 1016119110332, 14755861942091, 94597276047265, 1702584089571489

Offset

1,4

Links

Table of n, a(n) for n=1..29.

Crossrefs

Sequence in context: A070550 A298179 A185084 * A102762 A320783 A049853

Adjacent sequences: A145775 A145776 A145777 * A145779 A145780 A145781

Keyword

nonn

Author

R. H. Hardin, Oct 18 2008

Status

approved