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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.)