|
%I #13 Feb 27 2018 02:53:22
%S 42,78,146,274,514,966,1816,3414,6418,12066,22688,42658,80208,150808,
%T 283566,533182,1002538,1885048,3544452,6664608,12531430,23562750,
%U 44304934,83306386,156640636,294530672,553804746,1041316906,1957983912
%N Number of length n+3 0..2 arrays with no four consecutive terms having the maximum of any two terms equal to the minimum of the remaining two terms.
%C Column 2 of A250387.
%H R. H. Hardin, <a href="/A250381/b250381.txt">Table of n, a(n) for n = 1..210</a>
%F From _Colin Barker_, Aug 20 2017: (Start)
%F Empirical recurrence: a(n) = a(n-1) +2*a(n-2) -a(n-3) +3*a(n-4) -a(n-5) -7*a(n-6) +a(n-7) +a(n-10).
%F Empirical g.f.: 2*x*(21 + 18*x - 8*x^2 + 7*x^3 - 50*x^4 - 71*x^5 + 15*x^6 + 4*x^7 + 7*x^8 + 12*x^9) / (1 - x - 2*x^2 + x^3 - 3*x^4 + x^5 + 7*x^6 - x^7 - x^10).
%F (End)
%e Some solutions for n=6
%e ..1....1....2....2....1....0....2....1....0....0....1....0....1....0....2....1
%e ..0....2....0....0....0....0....1....2....1....2....0....2....0....1....0....0
%e ..0....2....1....2....1....1....2....2....2....1....2....2....2....0....0....2
%e ..2....1....2....0....0....2....0....0....0....0....0....1....0....1....1....0
%e ..2....0....0....1....1....2....2....1....2....2....2....0....1....0....1....2
%e ..0....2....2....0....0....1....1....2....1....2....0....2....2....1....0....1
%e ..1....2....1....2....2....0....2....0....0....1....1....0....0....0....0....0
%e ..2....0....2....2....0....2....1....0....2....0....2....2....0....2....1....2
%e ..2....1....1....0....2....2....2....2....0....2....2....0....2....2....1....0
%K nonn
%O 1,1
%A _R. H. Hardin_, Nov 20 2014
| 