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A250346 Number of length n arrays x(i), i=1..n with x(i) in i..i+3 and no value appearing more than 2 times.

%I A250346 #8 Nov 12 2018 15:40:07
%S A250346 4,16,62,235,888,3349,12620,47545,179104,674666,2541362,9572864,
%T A250346 36059224,135828387,511640114,1927252354,7259597884,27345542237,
%U A250346 103005522894,388002462425,1461532415920,5505318159061,20737499694808,78114267177504
%N A250346 Number of length n arrays x(i), i=1..n with x(i) in i..i+3 and no value appearing more than 2 times.
%H A250346 R. H. Hardin, <a href="/A250346/b250346.txt">Table of n, a(n) for n = 1..210</a>
%F A250346 Empirical: a(n) = 4*a(n-1) - 2*a(n-3) - 5*a(n-4) + a(n-6).
%F A250346 Empirical g.f.: x*(4 - 2*x^2 - 5*x^3 + x^5) / (1 - 4*x + 2*x^3 + 5*x^4 - x^6). - _Colin Barker_, Nov 12 2018
%e A250346 Some solutions for n=6:
%e A250346 ..3....1....1....1....3....1....1....0....3....2....1....2....0....1....0....0
%e A250346 ..2....2....3....4....2....1....4....4....4....2....3....4....2....2....3....1
%e A250346 ..5....4....2....2....3....4....2....3....2....4....3....5....2....2....4....2
%e A250346 ..4....5....3....4....6....6....6....3....6....5....4....5....6....3....3....4
%e A250346 ..5....4....4....7....4....5....5....5....5....4....6....7....7....5....7....5
%e A250346 ..6....5....5....5....6....8....5....5....5....5....7....7....6....6....8....5
%Y A250346 Column 3 of A250351.
%K A250346 nonn
%O A250346 1,1
%A A250346 _R. H. Hardin_, Nov 19 2014