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 A202072 #7 Jul 22 2025 16:28:10 %S A202072 14,120,264,0,3752,34632,80812,0,1201220,11395632,27164010,0, %T A202072 412081530,3962205256,9551670652,0,146582674200,1420696529280, %U A202072 3448764292020,0,53320604716082,519526871115120,1267129662479106,0,19692671314474548 %N A202072 Number of arrays of n+2 integers in -4..4 with sum zero and the sum of every adjacent pair being odd. %C A202072 Column 4 of A202076 %H A202072 R. H. Hardin, <a href="/A202072/b202072.txt">Table of n, a(n) for n = 1..210</a> %e A202072 Some solutions for n=3 %e A202072 .-4...-4....4....2....0....2....4....0....0....0...-2....4....2...-4...-4....4 %e A202072 ..3...-1...-1...-3....1....3....3....1...-3...-3....3...-1....1....3...-1...-1 %e A202072 ..0....4....2....2...-2....0...-4....4....2...-2...-4...-4....0....0....4...-4 %e A202072 .-1....3...-1...-3....1...-3...-3...-3....1....1...-1...-1....1...-3...-3...-3 %e A202072 ..2...-2...-4....2....0...-2....0...-2....0....4....4....2...-4....4....4....4 %K A202072 nonn %O A202072 1,1 %A A202072 _R. H. Hardin_ Dec 10 2011