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 A216984 Number of city-block distance 1, pressure limit 2 movements in an n X n array with each element moving exactly one horizontally or vertically, no element acquiring more than two neighbors, and without 2-loops 1
 0, 2, 264, 280900, 2891592224, 307860650044792, 342045101062468307160, 3979259269110908593906417328, 485168384985330726560602698774047840, 620116995791586597194849424436942942331423388 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Diagonal of A216991 LINKS R. H. Hardin, Table of n, a(n) for n = 1..11 EXAMPLE Some solutions for n=3 (movement: 0=n 1=e 2=s 3=w) ..1..2..3....1..2..3....2..3..3....1..2..3....1..2..3....1..1..2....2..3..3 ..2..2..3....0..3..2....1..2..0....1..1..0....0..3..3....0..2..3....2..0..3 ..1..1..0....0..3..3....0..3..3....0..3..3....0..1..0....0..1..0....1..0..0 CROSSREFS Sequence in context: A122862 A236437 A137105 * A007082 A135388 A238983 Adjacent sequences:  A216981 A216982 A216983 * A216985 A216986 A216987 KEYWORD nonn AUTHOR R. H. Hardin Sep 21 2012 STATUS approved

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Last modified October 16 13:32 EDT 2019. Contains 328093 sequences. (Running on oeis4.)