A145859 Number of n X n binary arrays symmetric under horizontal and vertical reflection with all ones connected only in two by two blocks.

1, 2, 1, 2, 2, 7, 5, 38, 12, 182, 72, 1536, 513, 21327, 4531, 360939, 68662, 9098657, 1429824, 345351393, 40840428, 18058986880, 1747979822, 1362075540043, 106711196102, 149443289019658, 9237029528023, 23324890541218597

Offset

1,2

Links

Table of n, a(n) for n=1..28.

Example

Maximal 7 X 7 example
.0.0.0.0.0.0.0
.1.1.0.0.0.1.1
.1.1.0.0.0.1.1
.0.0.0.0.0.0.0
.1.1.0.0.0.1.1
.1.1.0.0.0.1.1
.0.0.0.0.0.0.0

Crossrefs

Sequence in context: A077014 A093655 A023140 * A145863 A240492 A110775

Adjacent sequences: A145856 A145857 A145858 * A145860 A145861 A145862

Keyword

nonn

Author

R. H. Hardin, Oct 22 2008

Status

approved