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 A199525 #7 Jul 22 2025 13:19:47 %S A199525 1,6,36,212,1324,8342,53302,343710,2232322,14582218,95702528, %T A199525 630544704,4168091856,27630031358,183604587444,1222672695812, %U A199525 8157398577024,54515075729370,364861668341252,2445239266293460,16407415704050100 %N A199525 Number of -3..3 arrays x(0..n-1) of n elements with zero sum and no two consecutive zero elements. %C A199525 Column 3 of A199530 %H A199525 R. H. Hardin, <a href="/A199525/b199525.txt">Table of n, a(n) for n = 1..200</a> %e A199525 Some solutions for n=5 %e A199525 ..3...-2...-3...-1....0....1....3...-2....1....3...-2....0....1....2...-3....3 %e A199525 .-3....1....2....1....2....3....0....0...-3....3....0...-3...-3....1...-1...-2 %e A199525 ..2....1...-3....0...-2...-1....1....2....0...-3...-1....1....2...-2....3....1 %e A199525 .-3....3....3....1...-2...-1...-3...-2...-1....0....3....2....1...-3...-2...-2 %e A199525 ..1...-3....1...-1....2...-2...-1....2....3...-3....0....0...-1....2....3....0 %K A199525 nonn %O A199525 1,2 %A A199525 _R. H. Hardin_ Nov 07 2011