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A146638 Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 1010-1111-0100 pattern in any orientation. 0
1, 1, 1, 1, 1, 1, 1, 3, 9, 19, 33, 57, 181, 727, 3143, 12709, 46177, 203713, 1168453, 7869343, 57494841, 429662591, 3357500475 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,8

LINKS

Table of n, a(n) for n=1..23.

EXAMPLE

Maximal 8 X 8 example

.0.0.0.1.0.1.0.0

.0.0.1.1.1.1.0.0

.0.1.0.0.1.0.1.1

.1.1.0.0.0.1.1.0

.0.1.1.0.0.0.1.1

.1.1.0.1.0.0.1.0

.0.0.1.1.1.1.0.0

.0.0.1.0.1.0.0.0

CROSSREFS

Sequence in context: A328950 A049749 A147055 * A147135 A146843 A146630

Adjacent sequences:  A146635 A146636 A146637 * A146639 A146640 A146641

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 04 2008

STATUS

approved

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Last modified April 9 22:23 EDT 2020. Contains 333381 sequences. (Running on oeis4.)