A146018 Number of n X n binary arrays symmetric about main diagonal with all ones connected only in a 2X4 el 1,1 1,2 1,3 1,4 2,4 with any orientation.

1, 1, 1, 1, 3, 13, 41, 219, 1033, 8217, 92671, 1241193, 21102313, 438374597, 11919134635, 429471270295, 20089457592037, 1200700834920789, 91306423605321353, 8917989878582336861

Offset

1,5

Links

Table of n, a(n) for n=1..20.

Example

Maximal 8 X 8 example
.0.0.0.0.1.0.0.0
.0.0.0.0.1.0.0.1
.0.0.0.0.1.0.0.1
.0.0.0.0.1.1.0.1
.1.1.1.1.0.0.1.1
.0.0.0.1.0.0.0.0
.0.0.0.0.1.0.0.0
.0.1.1.1.1.0.0.0

Crossrefs

Sequence in context: A234387 A173867 A121162 * A145946 A109224 A106050

Adjacent sequences: A146015 A146016 A146017 * A146019 A146020 A146021

Keyword

nonn

Author

R. H. Hardin, Oct 26 2008

Status

approved