A146045 - OEIS

A146045

Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a 2X4 tee 1,1 1,2 1,3 2,3 1,4 in any orientation.

1, 1, 1, 5, 17, 49, 267, 1635, 15439, 178481, 2706563, 52897007, 1344799359, 42695435337, 1933850526571, 106233098774339

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,4

LINKS

EXAMPLE

Maximal 8 X 8 example

.0.0.0.0.1.1.1.1

.0.1.0.0.0.1.0.0

.1.1.1.1.0.0.1.0

.0.0.0.0.1.1.1.1

.1.1.1.1.0.0.0.0

.0.1.0.0.1.1.1.1

.0.0.1.0.0.0.1.0

.1.1.1.1.0.0.0.0

CROSSREFS

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 26 2008

STATUS

approved