A145946 Number of n X n binary arrays symmetric about main diagonal with all ones connected in a 3X2 elbow 1,1 1,2 1,3 2,3 in any orientation.

1, 1, 1, 3, 13, 41, 227, 1869, 21295, 308993, 6084845, 167200773, 6380227531, 331792369009, 23397509975499, 2257639231682789, 299410947515153649, 54437613856802551915, 13525155332080202787543, 4594219425445605883554215

Offset

1,4

Links

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

Example

Maximal 8 X 8 example
.0.0.1.1.0.1.1.1
.0.0.0.1.0.0.0.1
.1.0.0.1.0.1.1.0
.1.1.1.0.0.1.0.1
.0.0.0.0.0.1.0.1
.1.0.1.1.1.0.1.1
.1.0.1.0.0.1.0.0
.1.1.0.1.1.1.0.0

Crossrefs

Sequence in context: A173867 A121162 A146018 * A109224 A106050 A074425

Adjacent sequences: A145943 A145944 A145945 * A145947 A145948 A145949

Keyword

nonn

Author

R. H. Hardin, Oct 25 2008

Status

approved