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A145863 Number of n X n binary arrays symmetric under 90-degree rotation with all ones connected only in two by two blocks. 0
1, 2, 1, 2, 2, 7, 7, 22, 24, 108, 150, 786, 1301, 8045, 15509, 116985, 273970, 2472105, 6959192, 74864863, 250693524, 3242639202, 13050355068, 202176993015, 975396539666, 18089511084508, 104443510575847, 2322049495419469 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..28.

EXAMPLE

Maximal 7 X 7 example:

  0 0 0 0 0 0 0

  0 1 1 0 1 1 0

  0 1 1 0 1 1 0

  0 0 0 0 0 0 0

  0 1 1 0 1 1 0

  0 1 1 0 1 1 0

  0 0 0 0 0 0 0

CROSSREFS

Sequence in context: A093655 A023140 A145859 * A240492 A110775 A229232

Adjacent sequences:  A145860 A145861 A145862 * A145864 A145865 A145866

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 22 2008

STATUS

approved

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Last modified May 16 16:13 EDT 2022. Contains 353706 sequences. (Running on oeis4.)