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A246887 Number of length n+4 0..3 arrays with some pair in every consecutive five terms totalling exactly 3.

%I A246887 #6 Jun 02 2025 10:14:19
%S A246887 900,3364,12544,46656,173056,643204,2390116,8880400,32993536,
%T A246887 122589184,455480964,1692335044,6287855616,23362511104,86803301376,
%U A246887 322517224836,1198311166276,4452319442704,16542571369536,61463843852544
%N A246887 Number of length n+4 0..3 arrays with some pair in every consecutive five terms totalling exactly 3.
%C A246887 Column 3 of A246892
%H A246887 R. H. Hardin, <a href="/A246887/b246887.txt">Table of n, a(n) for n = 1..210</a>
%F A246887 Empirical: a(n) = 2*a(n-1) +4*a(n-2) +6*a(n-3) +12*a(n-4) -4*a(n-5) -6*a(n-6) -2*a(n-8) +a(n-10)
%e A246887 Some solutions for n=5
%e A246887 ..0....1....0....0....2....2....0....1....1....0....0....2....1....2....0....2
%e A246887 ..3....2....1....2....3....3....0....0....0....0....2....3....0....0....3....1
%e A246887 ..0....2....1....2....2....1....0....2....0....1....3....0....0....3....3....1
%e A246887 ..3....1....2....3....3....0....3....0....0....3....2....0....0....2....1....2
%e A246887 ..1....2....1....2....0....2....1....2....2....2....1....1....3....1....1....0
%e A246887 ..1....0....2....0....0....2....0....1....1....3....3....3....0....3....0....1
%e A246887 ..2....2....2....1....3....1....2....1....1....1....0....2....2....1....3....2
%e A246887 ..0....1....1....3....3....1....0....2....1....3....2....3....1....0....0....0
%e A246887 ..3....3....3....2....3....3....1....1....3....2....1....3....1....1....1....2
%K A246887 nonn
%O A246887 1,1
%A A246887 _R. H. Hardin_, Sep 06 2014