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 A198278 Number of 2nX2n 0..2 arrays with values 0..2 introduced in row major order and each element equal to exactly two horizontal and vertical neighbors 0
 1, 4, 100, 8784, 2823604, 3337609528 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Diagonal of A198285 LINKS EXAMPLE Some solutions for n=3 ..0..0..1..1..2..2....0..0..1..1..1..1....0..0..1..1..0..0....0..0..1..1..0..0 ..0..0..1..1..2..2....0..0..1..0..0..1....0..0..1..1..0..0....0..0..1..1..0..0 ..1..1..2..2..0..0....2..2..1..0..0..1....1..1..0..0..2..2....1..1..0..0..1..1 ..1..1..2..2..0..0....2..2..1..2..2..1....1..1..0..0..2..2....1..1..0..0..1..1 ..2..2..1..1..2..2....0..0..1..2..2..1....2..2..1..1..0..0....0..0..1..1..0..0 ..2..2..1..1..2..2....0..0..1..1..1..1....2..2..1..1..0..0....0..0..1..1..0..0 CROSSREFS Sequence in context: A224385 A249939 A224018 * A202990 A324096 A202989 Adjacent sequences:  A198275 A198276 A198277 * A198279 A198280 A198281 KEYWORD nonn AUTHOR R. H. Hardin Oct 23 2011 STATUS approved

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Last modified January 24 13:48 EST 2022. Contains 350538 sequences. (Running on oeis4.)