cp's OEIS Frontend

A250640 Number of length n+1 0..2 arrays with the sum of the maximum of each adjacent pair multiplied by some arrangement of +-1 equal to zero.

%I A250640 #8 Nov 15 2018 12:50:15
%S A250640 1,17,23,125,280,1061,2870,9495,27507,86149,255704,782393,2341381,
%T A250640 7090347,21271463,64109181,192439733,578665211,1736971814,5217197093,
%U A250640 15658051930,47004010481,141050402559,423295193635,1270100996174
%N A250640 Number of length n+1 0..2 arrays with the sum of the maximum of each adjacent pair multiplied by some arrangement of +-1 equal to zero.
%H A250640 R. H. Hardin, <a href="/A250640/b250640.txt">Table of n, a(n) for n = 1..210</a>
%F A250640 Empirical: a(n) = 6*a(n-1) - 3*a(n-2) - 42*a(n-3) + 71*a(n-4) + 56*a(n-5) - 192*a(n-6) + 80*a(n-7) + 77*a(n-8) - 64*a(n-9) + 12*a(n-10).
%F A250640 Empirical g.f.: x*(1 + 11*x - 76*x^2 + 80*x^3 + 242*x^4 - 541*x^5 + 201*x^6 + 239*x^7 - 192*x^8 + 36*x^9) / ((1 - x)*(1 - 2*x)*(1 + 2*x)*(1 - 3*x)*(1 - 3*x^2 + x^3)*(1 - 2*x - x^2 + x^3)). - _Colin Barker_, Nov 15 2018
%e A250640 Some solutions for n=6:
%e A250640 ..1....2....1....2....0....0....1....1....2....1....2....0....0....2....2....0
%e A250640 ..0....1....2....2....2....1....1....0....1....2....2....0....1....2....1....1
%e A250640 ..1....1....1....1....1....1....0....1....0....0....1....1....2....1....0....0
%e A250640 ..0....0....2....0....2....2....1....2....1....2....1....0....0....0....2....1
%e A250640 ..1....1....1....2....0....2....0....0....0....0....0....2....1....1....0....0
%e A250640 ..1....0....2....1....1....2....2....2....0....1....0....2....2....1....0....2
%e A250640 ..0....2....1....0....0....1....0....1....1....0....0....0....2....0....1....0
%Y A250640 Column 2 of A250646.
%K A250640 nonn
%O A250640 1,2
%A A250640 _R. H. Hardin_, Nov 26 2014