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%I #8 Sep 14 2013 02:22:38
%S 0,12,19920,6812201568,298259688517544784
%N Number of 2-cycle free city-block distance 1 permutations of a side-n hexagonal array.
%e Some solutions for n=3 (movement: 0=nw 1=ne 2=e 3=se 4=sw 5=w)
%e ......3.5.5..........3.5.5..........2.4.3..........2.4.3..........3.5.5
%e .....4.3.1.5........4.3.1.5........1.5.1.3........4.0.1.5........4.5.1.5
%e ....2.0.2.3.0......2.0.4.1.5......2.2.1.4.4......3.0.5.2.4......3.2.2.3.0
%e .....2.4.4.1........3.5.3.1........0.4.3.0........3.1.3.0........3.0.4.1
%e ......0.2.0..........2.1.1..........0.0.5..........1.1.5..........1.2.0
%K nonn,hard,more
%O 1,2
%A _R. H. Hardin_ Sep 18 2012
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