A145970 Number of n X n binary arrays symmetric under 90-degree rotation with all ones connected only in a 1 X 5 or 5 X 1 block.

1, 1, 1, 1, 1, 1, 4, 7, 15, 33, 90, 201, 647, 1861, 7123, 23236, 101280, 390759, 2050696, 9515925, 59455120, 328131409, 2431442671, 15797747304, 137926288897, 1064505557777

Offset

1,7

Links

Table of n, a(n) for n=1..26.

Example

Maximal 8 X 8 example:
  0 0 0 0 0 0 1 0
  1 1 1 1 1 0 1 0
  0 0 0 0 0 0 1 0
  0 1 0 0 0 0 1 0
  0 1 0 0 0 0 1 0
  0 1 0 0 0 0 0 0
  0 1 0 1 1 1 1 1
  0 1 0 0 0 0 0 0

Crossrefs

Sequence in context: A131935 A119749 A201498 * A232048 A145795 A173657

Adjacent sequences: A145967 A145968 A145969 * A145971 A145972 A145973

Keyword

nonn

Author

R. H. Hardin, Oct 25 2008

Status

approved