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%I #5 Mar 31 2012 12:36:20
%S 1,15422,418539642,14956351701700,628262652845622327,
%T 29351897757297625841299,1478434177099995753393526682,
%U 78758866558881824054985784506762,4381475477876207136274219572894470265
%N Number of permutations of n copies of 1..7 introduced in order 1..7 with no element equal to another within a distance of 2
%H R. H. Hardin, <a href="/A190928/b190928.txt">Table of n, a(n) for n = 1..19</a>
%e Some solutions for n=2
%e ..1....1....1....1....1....1....1....1....1....1....1....1....1....1....1....1
%e ..2....2....2....2....2....2....2....2....2....2....2....2....2....2....2....2
%e ..3....3....3....3....3....3....3....3....3....3....3....3....3....3....3....3
%e ..4....4....4....4....4....4....4....4....4....1....4....1....4....4....4....4
%e ..5....5....5....1....5....5....5....5....5....4....5....4....5....1....5....1
%e ..6....6....6....2....1....6....6....6....6....5....6....5....6....5....6....2
%e ..2....2....1....5....6....7....3....7....7....2....4....6....4....6....4....5
%e ..7....4....7....6....5....5....7....4....1....6....7....7....5....3....7....6
%e ..4....1....3....4....7....6....4....1....3....7....5....3....7....7....6....3
%e ..3....6....4....5....3....4....6....6....5....4....3....2....1....2....2....7
%e ..5....7....6....7....2....3....5....3....2....5....7....7....6....6....1....4
%e ..6....5....7....6....6....1....1....2....7....7....2....5....3....5....3....5
%e ..1....3....5....3....4....7....7....5....6....3....1....4....2....7....5....7
%e ..7....7....2....7....7....2....2....7....4....6....6....6....7....4....7....6
%K nonn
%O 1,2
%A _R. H. Hardin_ May 23 2011