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A146058 Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 2X3 U in any orientation. 0
1, 1, 1, 1, 1, 1, 3, 7, 13, 21, 51, 159, 577, 2001, 7625, 31703, 159573, 881761, 5519227, 36692597, 286423433, 2406566921, 23662937019, 247567053249, 2997634212141, 39099498214505, 595262340859501, 9726061577357237, 184962190180592957 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

LINKS

Table of n, a(n) for n=1..29.

EXAMPLE

Maximal 8 X 8 example

.0.0.0.1.1.0.0.0

.0.0.0.0.1.0.0.0

.0.0.0.1.1.0.0.0

.1.0.1.0.0.1.1.1

.1.1.1.0.0.1.0.1

.0.0.0.1.1.0.0.0

.0.0.0.1.0.0.0.0

.0.0.0.1.1.0.0.0

CROSSREFS

Sequence in context: A147501 A147335 A147464 * A155354 A136219 A078582

Adjacent sequences:  A146055 A146056 A146057 * A146059 A146060 A146061

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 26 2008

STATUS

approved

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Last modified January 26 03:23 EST 2022. Contains 350572 sequences. (Running on oeis4.)