A145932 Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a tee 1,1 1,2 1,3 2,2 in any orientation.

1, 1, 1, 5, 20, 85, 428, 3123, 34838, 454719, 8335296, 187056538, 6169076015, 247329264689, 14010937295624, 978281276679416, 99281241941019762, 12290336204514423117

Offset

1,4

Links

Table of n, a(n) for n=1..18.

Example

Maximal 8 X 8 example
.1.1.1.0.0.1.1.1
.0.1.0.0.0.0.1.0
.0.0.0.1.1.1.0.1
.1.0.0.0.1.0.1.1
.1.1.0.1.0.0.0.1
.1.0.1.1.1.0.0.0
.0.1.0.0.0.0.1.0
.1.1.1.0.0.1.1.1

Crossrefs

Sequence in context: A341920 A045499 A358518 * A026661 A099014 A219672

Adjacent sequences: A145929 A145930 A145931 * A145933 A145934 A145935

Keyword

nonn

Author

R. H. Hardin, Oct 25 2008

Status

approved