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 A201986 #7 Jul 22 2025 16:25:40 %S A201986 18,14107,11648559,7375608084,3674187761233,1507315600099908, %T A201986 526500713340421071,160321266022658991751,43304255513243305231273, %U A201986 10515069913569825177115136,2319701107323309166913311672 %N A201986 Number of nX4 zero-sum -3..3 arrays with rows and columns lexicographically nondecreasing. %C A201986 Column 4 of A201989 %H A201986 R. H. Hardin, <a href="/A201986/b201986.txt">Table of n, a(n) for n = 1..12</a> %e A201986 Some solutions for n=2 %e A201986 .-3.-3.-1..3...-3.-2..0..3...-2.-1.-1..2...-2..0..0..3...-3.-2.-1..3 %e A201986 .-1..0..2..3...-1..0..3..0....0..1..1..0...-1.-1..2.-1...-1..2..3.-1 %K A201986 nonn %O A201986 1,1 %A A201986 _R. H. Hardin_ Dec 07 2011