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%I #27 May 20 2021 01:26:00
%S 2,8,90,1876,103484,11462588,3118943536,1808994829500,
%T 2465526600093372,7394315828592829424,50975951518289853305508,
%U 784977037926751747674903856,27509351187362150581313065415008,2167705218542258344490649896364635660,387057670485382113845659790427906287869964
%N Number of binary arrangements without adjacent 1's on n X n array connected n-s nw-se.
%H Vaclav Kotesovec, <a href="/A067964/b067964.txt">Table of n, a(n) for n = 1..21</a>
%H V. Kotesovec, <a href="https://oeis.org/wiki/User:Vaclav_Kotesovec">Non-attacking chess pieces</a>, 6ed, 2013, p. 69-71.
%F Limit n->infinity (a(n))^(1/n^2) = 1.503048082... (see A085850)
%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 Cf. circle A000204, line A000045, arrays: ne-sw nw-se A067965, e-w ne-sw nw-se A067963, 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.
%K nonn,nice,hard
%O 1,1
%A _R. H. Hardin_, Feb 02 2002
%E Terms a(14)-a(18) from _Vaclav Kotesovec_, May 01 2012
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