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A246473 Number of length n+3 0..2 arrays with no pair in any consecutive four terms totalling exactly 2.

%I A246473 #8 Mar 19 2018 12:39:10
%S A246473 10,14,20,28,38,52,72,100,138,190,262,362,500,690,952,1314,1814,2504,
%T A246473 3456,4770,6584,9088,12544,17314,23898,32986,45530,62844,86742,119728,
%U A246473 165258,228102,314844,434572,599830,827932,1142776,1577348,2177178
%N A246473 Number of length n+3 0..2 arrays with no pair in any consecutive four terms totalling exactly 2.
%C A246473 Column 2 of A246479.
%H A246473 R. H. Hardin, <a href="/A246473/b246473.txt">Table of n, a(n) for n = 1..210</a>
%F A246473 Empirical: a(n) = a(n-1) + a(n-4).
%F A246473 Empirical g.f.: 2*x*(5 + 2*x + 3*x^2 + 4*x^3) / (1 - x - x^4). - _Colin Barker_, Mar 19 2018
%e A246473 Some solutions for n=6:
%e A246473 ..2....0....2....2....1....0....1....0....2....1....2....1....0....0....0....1
%e A246473 ..2....0....2....2....0....0....2....0....2....0....1....2....0....1....0....2
%e A246473 ..2....0....1....2....0....0....2....1....2....0....2....2....0....0....0....2
%e A246473 ..2....0....2....2....0....1....2....0....1....0....2....2....1....0....0....2
%e A246473 ..2....0....2....2....0....0....2....0....2....0....2....1....0....0....0....2
%e A246473 ..2....0....2....2....0....0....1....0....2....1....2....2....0....0....0....2
%e A246473 ..2....0....2....2....0....0....2....0....2....0....2....2....0....0....0....2
%e A246473 ..1....0....2....2....1....0....2....0....2....0....1....2....1....1....0....2
%e A246473 ..2....0....2....1....0....0....2....0....1....0....2....1....0....0....1....2
%Y A246473 Cf. A246479.
%K A246473 nonn
%O A246473 1,1
%A A246473 _R. H. Hardin_, Aug 27 2014