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 A199827 #7 Jul 22 2025 13:23:54 %S A199827 24,140,646,3556,20240,113884,645780,3685550,21117750,121503530, %T A199827 701432670,4060132070,23557575574,136975281374,797920002262, %U A199827 4655761528566,27205829211568,159187551327960,932560727269722 %N A199827 Number of -3..3 arrays x(0..n+1) of n+2 elements with zero sum and no two neighbors summing to zero. %C A199827 Column 3 of A199832 %H A199827 R. H. Hardin, <a href="/A199827/b199827.txt">Table of n, a(n) for n = 1..200</a> %e A199827 Some solutions for n=3 %e A199827 .-1...-2....3...-3....0....0...-3....2....1....0....1....2...-1....1....3....0 %e A199827 .-1...-3...-2...-2....2....1....1....3...-2....1....2...-1....2....3....0....1 %e A199827 ..3....0....1....3...-1...-3....3....1....0...-2...-1....2....1....1...-1....0 %e A199827 .-2....3...-3....3....2....0...-1...-3...-1...-1...-3...-3....0...-3...-2....2 %e A199827 ..1....2....1...-1...-3....2....0...-3....2....2....1....0...-2...-2....0...-3 %K A199827 nonn %O A199827 1,1 %A A199827 _R. H. Hardin_ Nov 11 2011