|
%I #4 Jan 17 2013 09:41:26
%S 0,7,49,392,3087,24353,192080,1515031,11949777,94253656,743424031,
%T 5863743809,46250174880,364797430823,2877333239921,22694914695208,
%U 179005735545903,1411904551687777,11136372010635760,87837935936264759
%N Number of 0..7 arrays of length n with each element unequal to at least one neighbor, starting with 0
%C Column 7 of A221463
%H R. H. Hardin, <a href="/A221462/b221462.txt">Table of n, a(n) for n = 1..134</a>
%F Empirical: a(n) = 7*a(n-1) +7*a(n-2)
%e Some solutions for n=6
%e ..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
%e ..6....5....5....7....7....1....7....4....1....3....1....4....2....5....6....1
%e ..1....4....5....3....2....2....4....7....1....5....2....3....5....2....7....2
%e ..1....1....0....4....0....3....6....5....2....1....4....3....1....7....3....5
%e ..4....6....4....4....3....7....1....2....1....1....2....0....0....4....5....1
%e ..2....2....6....7....0....1....2....0....5....2....1....4....6....0....0....0
%K nonn
%O 1,2
%A _R. H. Hardin_ Jan 17 2013
| 