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A145956 Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a zee 1,1 1,2 2,2 2,3 in any orientation. 0
1, 1, 1, 1, 1, 3, 7, 13, 37, 103, 343, 1549, 7241, 37919, 236383, 1636125, 13465687, 128312593, 1395150187, 17424865195, 251739719221, 4153202993611, 79756129711801, 1753738354816013, 44633769685103851, 1301658659951823679 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

LINKS

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

EXAMPLE

Maximal 8 X 8 example

.0.0.0.0.0.0.0.0

.0.0.0.0.1.1.0.0

.0.0.0.1.1.0.1.0

.0.0.1.0.0.1.1.0

.0.1.1.0.0.1.0.0

.0.1.0.1.1.0.0.0

.0.0.1.1.0.0.0.0

.0.0.0.0.0.0.0.0

CROSSREFS

Sequence in context: A177945 A147448 A146449 * A155225 A051842 A147447

Adjacent sequences: A145953 A145954 A145955 * A145957 A145958 A145959

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 25 2008

STATUS

approved

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Last modified March 26 17:14 EDT 2023. Contains 361551 sequences. (Running on oeis4.)