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A187458 Number of (n+1)X(n+1) 0..1 arrays with all the 2X2 subblocks nonsingular and the array of 2X2 subblock determinants symmetric 1
6, 26, 144, 1272, 15192, 286392, 7648032, 314011868, 18986004296, 1725663296600, 237096836118080, 48071903199959400, 15027587384189632928, 6819730931931151055960, 4852231403635188536789728 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A187462

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..18

EXAMPLE

Some solutions for 4X4

..1..1..0..1....1..0..1..1....0..1..0..1....1..0..1..1....1..0..1..0

..1..0..1..0....0..1..0..1....1..0..1..0....0..1..0..1....1..1..1..1

..0..1..0..1....1..0..1..1....1..1..0..1....1..0..1..1....1..0..1..0

..1..0..1..1....0..1..0..1....1..0..1..1....1..1..1..0....0..1..1..1

CROSSREFS

Sequence in context: A046233 A140231 A144037 * A100308 A049040 A103649

Adjacent sequences:  A187455 A187456 A187457 * A187459 A187460 A187461

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 10 2011

STATUS

approved

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Last modified August 8 05:25 EDT 2020. Contains 336290 sequences. (Running on oeis4.)