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A201082 Number of -2..2 arrays of n elements with first and second differences also in -2..2.

%I A201082 #8 Feb 15 2018 09:24:11
%S A201082 5,19,57,175,537,1653,5089,15663,48207,148375,456685,1405633,4326401,
%T A201082 13316243,40986117,126151337,388281713,1195093865,3678384289,
%U A201082 11321714051,34847150005,107256185601,330124252601,1016090788147,3127429995345
%N A201082 Number of -2..2 arrays of n elements with first and second differences also in -2..2.
%C A201082 Column 2 of A201088.
%H A201082 R. H. Hardin, <a href="/A201082/b201082.txt">Table of n, a(n) for n = 1..210</a>
%F A201082 Empirical: a(n) = 3*a(n-1) +a(n-2) -2*a(n-3) -2*a(n-5) -4*a(n-6) +2*a(n-8) +a(n-9).
%F A201082 Empirical g.f.: x*(1 + x)*(5 - x - 4*x^2 - x^3 - 6*x^4 - 3*x^5 + 4*x^6 + 3*x^7) / (1 - 3*x - x^2 + 2*x^3 + 2*x^5 + 4*x^6 - 2*x^8 - x^9). - _Colin Barker_, Feb 15 2018
%e A201082 Some solutions for n=9:
%e A201082 ..0....1....1...-2...-2...-1....2....2....0....2....0....0....0....1...-2....2
%e A201082 ..0....0....0...-1....0....0....1....2...-1....2....1....1....2...-1...-2....2
%e A201082 .-1...-2....0...-1....0....0....0....1....0....0....0....0....2...-1...-1....2
%e A201082 .-1...-2....1...-1....0....0....1....1....1....0...-1....1....1....1....0....0
%e A201082 .-1....0....1...-1...-2...-2....0....2....2....1...-2....0....2....1....0....0
%e A201082 ..0....0....2....0...-2...-2...-1....2....2....0...-1...-1....1....1...-1...-2
%e A201082 .-1...-1....1...-1...-1...-1...-2....2....2....1....0...-2...-1....1...-1...-2
%e A201082 .-1...-2....0...-1...-2....0...-1....0....1....1....0...-2...-1....0...-1...-1
%e A201082 ..0...-2....1...-2...-2...-1...-2....0....0....1....0...-1....0....0....0....1
%K A201082 nonn
%O A201082 1,1
%A A201082 _R. H. Hardin_, Nov 26 2011