Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #21 Aug 22 2016 16:52:56
%S 2,7,77,1152,56549,3837761,806190208,251170142257,223733272186825,
%T 319544298135448960,1210302996752248488817,7876274672755293629849313,
%U 127662922218147601317696761088,3758866349549535184419575245899295
%N Number of binary arrangements without adjacent 1's on n X n array connected e-w ne-sw nw-se.
%H R. H. Hardin and Vaclav Kotesovec, <a href="/A067963/b067963.txt">Table of n, a(n) for n = 1..30</a>
%H V. Kotesovec, <a href="https://oeis.org/wiki/User:Vaclav_Kotesovec">Non-attacking chess pieces</a>, 6ed, 2013, p. 69-71.
%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, 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 Diagonal of A228683
%K nonn,nice,hard
%O 1,1
%A _R. H. Hardin_, Feb 02 2002
%E Terms a(15)-a(19) from _Vaclav Kotesovec_, May 01 2012