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 A211052 1/3 the number of n X n 0..2 symmetric matrices with every element equal to one, two or three horizontal and vertical neighbors 1
 0, 1, 9, 239, 14669, 2313041, 915560157, 915512113455, 2309733753013069, 14705975948890342013, 236286306641789616616527, 9580759647090339471565196845, 980341335177418943590433413869387 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS R. H. Hardin, Table of n, a(n) for n = 1..14 EXAMPLE Some solutions for n=4 ..0..0..1..0....1..1..2..2....1..1..0..0....2..2..0..2....0..0..1..1 ..0..1..1..0....1..1..2..1....1..1..1..1....2..2..0..2....0..0..2..2 ..1..1..1..1....2..2..1..1....0..1..1..0....0..0..2..2....1..2..2..2 ..0..0..1..1....2..1..1..1....0..1..0..0....2..2..2..2....1..2..2..2 CROSSREFS Sequence in context: A157569 A279492 A297747 * A085799 A278858 A274789 Adjacent sequences:  A211049 A211050 A211051 * A211053 A211054 A211055 KEYWORD nonn AUTHOR R. H. Hardin Mar 30 2012 STATUS approved

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Last modified January 25 01:46 EST 2020. Contains 331229 sequences. (Running on oeis4.)