cp's OEIS Frontend

A221461 Number of 0..6 arrays of length n with each element unequal to at least one neighbor, starting with 0.

%I A221461 #6 Jun 02 2025 08:21:01
%S A221461 0,6,36,252,1728,11880,81648,561168,3856896,26508384,182191680,
%T A221461 1252200384,8606352384,59151316608,406546013952,2794183983360,
%U A221461 19204379983872,131991383803392,907174582723584,6234995799161856
%N A221461 Number of 0..6 arrays of length n with each element unequal to at least one neighbor, starting with 0.
%C A221461 Column 6 of A221463
%H A221461 R. H. Hardin, <a href="/A221461/b221461.txt">Table of n, a(n) for n = 1..135</a>
%F A221461 Empirical: a(n) = 6*a(n-1) +6*a(n-2)
%e A221461 Some solutions for n=6
%e A221461 ..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
%e A221461 ..6....4....2....3....2....4....2....6....3....3....1....2....1....5....5....3
%e A221461 ..3....2....5....0....2....5....1....6....2....1....2....4....4....5....0....3
%e A221461 ..4....4....4....3....6....3....2....2....0....4....2....0....0....4....0....0
%e A221461 ..4....3....6....6....1....5....2....2....5....6....3....4....3....0....5....3
%e A221461 ..6....4....4....2....6....0....3....4....3....2....6....2....6....4....1....4
%K A221461 nonn
%O A221461 1,2
%A A221461 _R. H. Hardin_ Jan 17 2013