A145930 Number of n X n binary arrays symmetric about the diagonal and under 90-degree rotation with all ones connected only in a tee 1,1 1,2 1,3 2,2 in any orientation.

1, 1, 1, 1, 2, 1, 4, 1, 10, 3, 38, 10, 203, 33, 1282, 134, 10692, 947, 122622, 8780, 1931387, 97821, 38646298, 1375312, 1027005070, 27712816, 36128007770, 754977953, 1725393598658, 26645291289

Offset

1,5

Links

Table of n, a(n) for n=1..30.

Example

Maximal 9 X 9 example:
  0 1 1 1 0 1 1 1 0
  1 0 1 0 1 0 1 0 1
  1 1 0 1 1 1 0 1 1
  1 0 1 0 0 0 1 0 1
  0 1 1 0 0 0 1 1 0
  1 0 1 0 0 0 1 0 1
  1 1 0 1 1 1 0 1 1
  1 0 1 0 1 0 1 0 1
  0 1 1 1 0 1 1 1 0

Crossrefs

Sequence in context: A104620 A243913 A186724 * A145762 A024539 A128271

Adjacent sequences: A145927 A145928 A145929 * A145931 A145932 A145933

Keyword

nonn

Author

R. H. Hardin, Oct 25 2008

Status

approved