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 A199841 #8 Jul 22 2025 13:24:59 %S A199841 1,3,8,23,66,192,575,1739,5307,16304,50381,156408,487398,1523663, %T A199841 4776107,15006513,47247134,149023605,470794024,1489462276,4718330397, %U A199841 14964219411,47509518289,150982994162,480243297965,1528796563830,4870415108094 %N A199841 Number of -2..2 arrays x(0..n-1) of n elements with zero sum and no element more than one greater than the previous. %C A199841 Column 2 of A199847 %H A199841 R. H. Hardin, <a href="/A199841/b199841.txt">Table of n, a(n) for n = 1..200</a> %e A199841 Some solutions for n=6 %e A199841 ..2...-1....2....1....2....1....1....1....1...-1....2....1....1....1....1....1 %e A199841 ..1....0....0...-1....1....1....2....1...-1....0....2....1....1....2....0....0 %e A199841 .-2....1....1....0....2....0....0....0...-1....1...-2....1....1....1....0...-1 %e A199841 .-1....0...-2....0...-1...-1....0....1....0....1...-1....0...-1...-1....0....0 %e A199841 ..0....1...-1....0...-2....0...-2...-2....0....1...-1...-1....0...-1....1....0 %e A199841 ..0...-1....0....0...-2...-1...-1...-1....1...-2....0...-2...-2...-2...-2....0 %K A199841 nonn %O A199841 1,2 %A A199841 _R. H. Hardin_ Nov 11 2011