Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #4 Apr 18 2012 05:38:27
%S 69,173,375,765,1545,3029,5973,11621,22759,44341,86833,169841,333421,
%T 654917,1289687,2542733,5021945,9931349,19663237,38977973,77326087,
%U 153558325,305104801,606719185,1206917981,2402499477,4783531511
%N Number of -4..4 arrays x(i) of n+1 elements i=1..n+1 with x(i)+x(j), x(i+1)+x(j+1), -(x(i)+x(j+1)), and -(x(i+1)+x(j)) having one or three distinct values for every i<=n and j<=n
%H R. H. Hardin, <a href="/A211688/b211688.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 3*a(n-1) +10*a(n-2) -35*a(n-3) -35*a(n-4) +160*a(n-5) +45*a(n-6) -365*a(n-7) +6*a(n-8) +437*a(n-9) -55*a(n-10) -260*a(n-11) +30*a(n-12) +60*a(n-13)
%e Some solutions for n=5
%e .-2...-4....4....1....2....2....0....0....2...-4....1....0....3....0....0....0
%e ..2....0....2....2....0....0....3....0....0...-3....0....4....2....2...-1...-3
%e ..0....4....4....1....0....0....0....4....2...-2....1...-4....1...-2....1....0
%e .-2....0....2....2....2....0....0....0...-2...-1....2....4....2....0....0....0
%e ..2....0....0....3....0...-4....0....0....0....0....3....0....1...-2....1...-3
%e .-2....4....2....4...-1....0....0...-4....2...-1....4....4....0....0...-1....0
%K nonn
%O 1,1
%A _R. H. Hardin_ Apr 18 2012