A211593 - OEIS

%I #4 Apr 16 2012 07:05:35

%S 17,61,189,537,1405,3605,8909,22093,53669,131917,319837,786941,

%T 1915309,4734125,11587605,28797317,70895933,177097381,438296237,

%U 1099734997,2734106629,6885392301,17183667245,43402287421,108663538381,275107471725

%N Number of -2..2 arrays x(i) of n+1 elements i=1..n+1 with set{t,u,v in 0,1}((x[i+t]+x[j+u]+x[k+v])*(-1)^(t+u+v)) having one, three, four, five, six or eight distinct values for every i,j,k<=n

%H R. H. Hardin, <a href="/A211593/b211593.txt">Table of n, a(n) for n = 1..51</a>

%F Empirical: a(n) = 4*a(n-1) +17*a(n-2) -81*a(n-3) -105*a(n-4) +675*a(n-5) +245*a(n-6) -3021*a(n-7) +198*a(n-8) +7895*a(n-9) -2282*a(n-10) -12190*a(n-11) +4928*a(n-12) +10646*a(n-13) -4768*a(n-14) -4680*a(n-15) +2016*a(n-16) +792*a(n-17) -288*a(n-18)

%e Some solutions for n=5

%e ..1....2...-1....0...-2...-2....2....1....0....2....0...-2...-1....2....1...-1

%e ..2....0....2....0....1....0....1...-2....0....1...-1....0....2....0....0...-2

%e ..0...-2...-1....0...-2....2....2....0....0....0....0....2....1....0....0...-1

%e ..1....0...-2....1...-1....0...-1...-2...-1...-2...-1....0....0...-2...-2....0

%e ..0...-2...-1....0...-2...-2...-2....1....0...-1....0....2....1....0...-1...-2

%e ..2....1....2...-2...-1....1...-1....2....2...-2....1....0....0....0...-2....0

%K nonn

%O 1,1

%A _R. H. Hardin_ Apr 16 2012