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%I #7 Nov 08 2018 08:53:11
%S 42,70,118,198,342,590,1014,1766,3062,5286,9222,16006,27654,48262,
%T 83782,144774,252678,438662,758022,1323014,2296838,3969030,6927366,
%U 12026374,20782086,36272134,62970886,108816390,189923334,329719814,569769990
%N Number of length n+2 0..5 arrays with every three consecutive terms having the sum of some two elements equal to twice the third.
%H R. H. Hardin, <a href="/A248430/b248430.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = a(n-1) + 6*a(n-3) - 6*a(n-4) - 4*a(n-6) + 4*a(n-7).
%F Empirical g.f.: 2*x*(21 + 14*x + 24*x^2 - 86*x^3 - 12*x^4 - 20*x^5 + 56*x^6) / ((1 - x)*(1 - 6*x^3 + 4*x^6)). - _Colin Barker_, Nov 08 2018
%e Some solutions for n=6:
%e ..2....0....4....1....1....5....3....5....1....0....5....2....5....4....5....2
%e ..0....1....0....3....2....1....1....3....5....2....4....1....1....0....1....4
%e ..1....2....2....2....3....3....2....4....3....1....3....3....3....2....3....0
%e ..2....3....4....4....1....2....3....5....4....3....2....5....5....1....2....2
%e ..0....4....0....3....2....1....4....3....5....2....1....1....1....3....4....1
%e ..4....2....2....5....3....3....5....1....3....4....0....3....3....5....3....3
%e ..2....3....1....1....1....2....3....2....4....3....2....5....5....4....2....2
%e ..3....1....0....3....2....4....4....0....2....2....4....1....4....3....4....1
%Y Column 5 of A248433.
%K nonn
%O 1,1
%A _R. H. Hardin_, Oct 06 2014
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