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A141508 Number of n X n binary matrices, symmetric under 180 degree rotation, with no more than 2 ones in any 2 X 2 subblock. 0
1, 2, 3, 19, 93, 1575, 21225, 1007325, 39296735, 5294789855, 584025270873, 223173910768577, 70041418150889563, 76024730608891641301, 67725956302664583147084, 208747768532396398250753135, 528233319697505378983008951127 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..16.

CROSSREFS

Sequence in context: A262957 A072263 A009178 * A119344 A072877 A201378

Adjacent sequences:  A141505 A141506 A141507 * A141509 A141510 A141511

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 10 2008

STATUS

approved

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Last modified May 30 15:05 EDT 2020. Contains 334726 sequences. (Running on oeis4.)