This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A199699 #10 Jul 22 2025 13:22:27 %S A199699 1,6,32,168,892,4964,27854,156920,891684,5095360,29236016,168361392, %T A199699 972601784,5633548460,32706291872,190266981972,1108856802378, %U A199699 6472638961608,37836350087956,221461180199752,1297757839607606 %N A199699 Number of -3..3 arrays x(0..n-1) of n elements with zero sum and no two neighbors equal. %C A199699 Column 3 of A199704 %H A199699 R. H. Hardin, <a href="/A199699/b199699.txt">Table of n, a(n) for n = 1..200</a> %e A199699 Some solutions for n=5 %e A199699 ..1....0....2...-3....1...-3...-2...-3...-2....0....1....2....2....2...-2....0 %e A199699 .-1....1....0....1....2....2....1....3...-1....2....2....0....0...-2...-3....3 %e A199699 .-3...-1....1...-2...-2....1...-2....0....0....1...-3...-1...-3....3....3....2 %e A199699 ..3...-2...-3....1....0...-2....2....1....3...-2....1....1...-1...-1....2...-3 %e A199699 ..0....2....0....3...-1....2....1...-1....0...-1...-1...-2....2...-2....0...-2 %K A199699 nonn %O A199699 1,2 %A A199699 _R. H. Hardin_ Nov 09 2011