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%I #36 May 21 2021 04:16:41
%S 2,9,119,2704,177073,21836929,6985036032,4576976735769,
%T 7263963336910751,24830487842030082304,198126078679714777857441,
%U 3494153303407491549112098721,141264727800378056245286463971328,12779122891585386852029424628087941481,2628141044813862018744988536642011269669959
%N Number of binary arrangements without adjacent 1's on n X n array connected ne-sw and nw-se.
%H Vaclav Kotesovec, <a href="/A067965/b067965.txt">Table of n, a(n) for n = 1..19</a>
%H V. Kotesovec, <a href="https://oeis.org/wiki/User:Vaclav_Kotesovec">Non-attacking chess pieces</a>, 6ed, 2013, p. 69, 417.
%e Neighbors for n=4 (dots represent spaces):
%e . o..o..o..o
%e ...\/ \/ \/
%e .../\ /\ /\
%e . o..o..o..o
%e ...\/ \/ \/
%e .../\ /\ /\
%e . o..o..o..o
%e ...\/ \/ \/
%e .../\ /\ /\
%e . o..o..o..o
%Y Main diagonal of A181212.
%Y 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.
%Y Cf. A201861, A212271.
%K nonn,nice,hard
%O 1,1
%A _R. H. Hardin_, Feb 02 2002
%E Term a(14) from _Vaclav Kotesovec_, Dec 06 2011
%E Term a(15) from _Vaclav Kotesovec_, Jan 03 2012
%E Term a(16) from _Vaclav Kotesovec_, May 01 2012
%E Term a(17)-a(18) from _Vaclav Kotesovec_, Aug 13 2016
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