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A146148 Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in an em 1,1 1,2 2,2 2,3 3,3 in any orientation. 0
1, 1, 1, 3, 5, 7, 25, 61, 137, 491, 1895, 6799, 35271, 188161, 1045823, 6942831, 54475785, 429190219, 4220050567, 45840848045, 555820995851, 7424820570827, 118936859724455, 2001479983540325, 39919686781316217, 873987056828886899 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..26.

EXAMPLE

Maximal 8 X 8 example

.0.0.1.0.0.1.1.0

.0.1.1.0.0.0.1.1

.1.1.0.1.1.0.0.1

.0.0.1.0.1.1.0.0

.0.0.1.1.0.1.0.0

.1.0.0.1.1.0.1.1

.1.1.0.0.0.1.1.0

.0.1.1.0.0.1.0.0

CROSSREFS

Sequence in context: A029846 A108313 A045966 * A098475 A131039 A294924

Adjacent sequences:  A146145 A146146 A146147 * A146149 A146150 A146151

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 27 2008

STATUS

approved

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Last modified February 24 13:13 EST 2021. Contains 341569 sequences. (Running on oeis4.)