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A146048 Number of n X n binary arrays symmetric under horizontal and vertical reflection with all ones connected only in a 2X2 block with tail 1,1 1,2 1,3 2,2 2,3 in any orientation. 0
1, 1, 1, 1, 1, 1, 17, 17, 57, 57, 781, 781, 24351, 24351, 931801, 931801, 62200649, 62200649, 8963823755, 8963823755, 2146203654665, 2146203654665, 870522837091137, 870522837091137, 672438522925983773 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

LINKS

Table of n, a(n) for n=1..25.

EXAMPLE

Maximal 8 X 8 example

.0.0.0.0.0.0.0.0

.1.1.0.0.0.0.1.1

.1.1.1.0.0.1.1.1

.0.0.0.0.0.0.0.0

.0.0.0.0.0.0.0.0

.1.1.1.0.0.1.1.1

.1.1.0.0.0.0.1.1

.0.0.0.0.0.0.0.0

CROSSREFS

Sequence in context: A147241 A146580 A146455 * A146809 A147233 A146817

Adjacent sequences:  A146045 A146046 A146047 * A146049 A146050 A146051

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 26 2008

STATUS

approved

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Last modified October 5 10:20 EDT 2022. Contains 357255 sequences. (Running on oeis4.)