A146046 Number of n X n binary arrays with all ones connected only in a 2X2 block with tail 1,1 1,2 1,3 2,2 2,3 in any orientation.

1, 1, 17, 57, 781, 24351, 931801, 62200649, 8963823755, 2146203654665, 870522837091137, 672438522925983773

Offset

1,3

Links

Table of n, a(n) for n=1..12.

Example

Maximal 8 X 8 example
.1.1.0.1.1.1.0.0
.1.1.0.1.1.0.1.1
.1.0.1.0.0.0.1.1
.0.1.1.0.1.1.0.1
.0.1.1.0.1.1.0.0
.1.0.0.1.0.1.0.1
.1.1.0.1.1.0.1.1
.1.1.0.1.1.0.1.1

Crossrefs

Sequence in context: A264473 A146578 A146453 * A048508 A020879 A029914

Adjacent sequences: A146043 A146044 A146045 * A146047 A146048 A146049

Keyword

nonn

Author

R. H. Hardin, Oct 26 2008

Status

approved