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 A211051 1/3 the number of n X n 0..2 symmetric matrices with every element equal to zero, two or three horizontal and vertical neighbors 0
 1, 5, 45, 801, 27967, 1940165, 265677267, 71849269093, 38284388785363, 40154074645523977, 82859490626738386321, 336329579954192837096611, 2685093328682215861465741329 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..13. EXAMPLE Some solutions for n=4 ..0..1..0..0....0..1..0..1....2..0..2..0....2..2..2..2....2..1..2..2 ..1..0..0..0....1..2..1..2....0..1..0..1....2..0..1..2....1..2..2..2 ..0..0..2..1....0..1..2..0....2..0..1..0....2..1..2..2....2..2..2..2 ..0..0..1..2....1..2..0..1....0..1..0..2....2..2..2..0....2..2..2..2 CROSSREFS Sequence in context: A155104 A243951 A290941 * A322661 A191962 A326650 Adjacent sequences: A211048 A211049 A211050 * A211052 A211053 A211054 KEYWORD nonn AUTHOR R. H. Hardin Mar 30 2012 STATUS approved

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Last modified June 19 03:10 EDT 2024. Contains 373492 sequences. (Running on oeis4.)