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 A202246 #8 Jun 02 2025 07:24:36 %S A202246 1,3,9,31,107,387,1415,5231,19477,72933,274339,1035807,3923229, %T A202246 14900005,56721943,216377047,826917803,3165318823,12133973901, %U A202246 46575395693,178988128029,688588254425,2651686966607,10220607799703,39426825300181 %N A202246 Number of zero-sum -2..2 arrays of n elements with adjacent element differences also in -2..2. %C A202246 Column 2 of A202252 %H A202246 R. H. Hardin, <a href="/A202246/b202246.txt">Table of n, a(n) for n = 1..210</a> %e A202246 Some solutions for n=10 %e A202246 ..0....2....1...-1...-2....2....0....0...-1....2....1...-1....0....2....1....1 %e A202246 ..1....0....0....1....0....0....0...-1....1....2...-1...-1...-1....0...-1....0 %e A202246 ..2....0....0...-1...-1...-1....1...-2....1....2....1....1...-1....2...-1...-1 %e A202246 ..1...-2...-2....1....0....0...-1....0....0....0....0....1...-1....2....1...-2 %e A202246 ..1....0...-2....1....0....2...-2....0...-1...-1...-2....0....1....1...-1....0 %e A202246 ..0....0....0...-1....2....0....0....1....0...-2....0...-1...-1...-1....0....0 %e A202246 .-1....0....2...-1....1...-2....0....0...-1...-2....2....1....0....0....0....2 %e A202246 .-2...-2....1....0....1...-1....0....1....1...-2....0....1....0...-2....0....2 %e A202246 .-2....0...-1....1....0....1....0....0....1....0...-1....0....2...-2....0....0 %e A202246 ..0....2....1....0...-1...-1....2....1...-1....1....0...-1....1...-2....1...-2 %K A202246 nonn %O A202246 1,2 %A A202246 _R. H. Hardin_ Dec 14 2011