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A145930 Number of n X n binary arrays symmetric about the diagonal and under 90-degree rotation with all ones connected only in a tee 1,1 1,2 1,3 2,2 in any orientation. 0
1, 1, 1, 1, 2, 1, 4, 1, 10, 3, 38, 10, 203, 33, 1282, 134, 10692, 947, 122622, 8780, 1931387, 97821, 38646298, 1375312, 1027005070, 27712816, 36128007770, 754977953, 1725393598658, 26645291289 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Table of n, a(n) for n=1..30.

EXAMPLE

Maximal 9 X 9 example:

  0 1 1 1 0 1 1 1 0

  1 0 1 0 1 0 1 0 1

  1 1 0 1 1 1 0 1 1

  1 0 1 0 0 0 1 0 1

  0 1 1 0 0 0 1 1 0

  1 0 1 0 0 0 1 0 1

  1 1 0 1 1 1 0 1 1

  1 0 1 0 1 0 1 0 1

  0 1 1 1 0 1 1 1 0

CROSSREFS

Sequence in context: A104620 A243913 A186724 * A145762 A024539 A128271

Adjacent sequences:  A145927 A145928 A145929 * A145931 A145932 A145933

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 25 2008

STATUS

approved

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Last modified January 28 00:32 EST 2020. Contains 331313 sequences. (Running on oeis4.)