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%I #21 Nov 24 2018 09:03:49
%S 1,47844,4420321081,551248360550999,81644850343968535401,
%T 13519747358522016160671387,2421032324142610480402567434373,
%U 459408385876250801291447710561829082,91155245844064069307740171414201519055298
%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 1.
%H Seiichi Manyama, <a href="/A190927/b190927.txt">Table of n, a(n) for n = 1..185</a> (terms 1..25 from R. H. Hardin)
%F a(n) ~ 343 * sqrt(7) * 2^(7*n-8) * 3^(7*n-3) / (625 * Pi^3 * n^3). - _Vaclav Kotesovec_, Nov 24 2018
%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 2 2 4 4 4 2 4 4 4 4 2
%e 5 5 5 1 5 4 4 2 5 5 4 2 1 3 2 1
%e 6 6 6 5 6 5 3 5 3 6 5 4 4 5 5 4
%e 2 7 4 6 7 6 5 6 6 3 6 5 5 6 6 5
%e 7 3 5 4 2 3 6 5 7 7 7 1 6 4 4 6
%e 5 4 2 2 1 5 7 6 2 6 3 6 7 5 7 7
%e 6 5 6 3 6 4 5 1 4 1 7 3 2 7 1 3
%e 4 6 1 5 7 7 7 3 7 7 5 7 5 2 7 4
%e 3 2 7 7 5 1 1 7 1 5 1 6 7 1 5 6
%e 7 7 3 6 4 6 6 4 5 4 6 5 6 7 6 7
%e 1 1 7 7 3 7 4 7 6 2 4 7 3 6 3 5
%Y Cf. A000012 (b=2), A190917 (b=3), A190918 (b=4), A190920 (b=5), A190923 (b=6), A190932 (b=8), A321987 (b=9).
%K nonn
%O 1,2
%A _R. H. Hardin_, May 23 2011
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