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 A067965 Number of binary arrangements without adjacent 1's on n X n array connected ne-sw and nw-se. 13
 2, 9, 119, 2704, 177073, 21836929, 6985036032, 4576976735769, 7263963336910751, 24830487842030082304, 198126078679714777857441, 3494153303407491549112098721, 141264727800378056245286463971328, 12779122891585386852029424628087941481, 2628141044813862018744988536642011269669959 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Vaclav Kotesovec, Table of n, a(n) for n = 1..18 V. Kotesovec, Non-attacking chess pieces, 6ed, 2013, p. 69, 417. EXAMPLE Neighbors for n=4 (dots represent spaces): . o..o..o..o ...\/ \/ \/ .../\ /\ /\ . o..o..o..o ...\/ \/ \/ .../\ /\ /\ . o..o..o..o ...\/ \/ \/ .../\ /\ /\ . o..o..o..o CROSSREFS Main diagonal of A181212. Cf. circle A000204, line A000045, arrays: e-w ne-sw nw-se A067963, n-s nw-se A067964, e-w n-s nw-se A066864, e-w ne-sw n-s nw-se A063443, n-s A067966, e-w n-s A006506, nw-se A067962, toruses: bare A002416, ne-sw nw-se A067960, ne-sw n-s nw-se A067959, e-w ne-sw n-s nw-se A067958, n-s A067961, e-w n-s A027683, e-w ne-sw n-s A066866. Cf. A201861, A212271. Sequence in context: A307249 A201381 A075538 * A237999 A194017 A135543 Adjacent sequences:  A067962 A067963 A067964 * A067966 A067967 A067968 KEYWORD nonn,nice,hard AUTHOR R. H. Hardin, Feb 02 2002 EXTENSIONS Term a(14) from Vaclav Kotesovec, Dec 06 2011 Term a(15) from Vaclav Kotesovec, Jan 03 2012 Term a(16) from Vaclav Kotesovec, May 01 2012 Term a(17)-a(18) from Vaclav Kotesovec, Aug 13 2016 STATUS approved

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Last modified April 4 04:02 EDT 2020. Contains 333212 sequences. (Running on oeis4.)