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 A201984 #7 Jul 22 2025 16:25:27 %S A201984 4,77,1170,14107,139471,1177568,8721417,57801225,347923603,1924356711, %T A201984 9871703167,47329086175,213435856527,910247506472,3688234465315, %U A201984 14255722610693,52746861442115,187406263165391,641125854338628 %N A201984 Number of nX2 zero-sum -3..3 arrays with rows and columns lexicographically nondecreasing. %C A201984 Column 2 of A201989 %H A201984 R. H. Hardin, <a href="/A201984/b201984.txt">Table of n, a(n) for n = 1..177</a> %e A201984 Some solutions for n=5 %e A201984 .-3..2...-3.-2...-3..2...-3..2...-3..3...-3.-2...-3.-1...-3.-3...-2.-2...-3..1 %e A201984 .-2.-2...-3.-1...-2.-1...-3..2...-1.-2...-3..2...-2..1...-3..3...-2..3...-2..1 %e A201984 ..0.-1....0..1...-1..2...-2..2...-1..0...-2..1....0.-3...-1..1....0.-2...-2..3 %e A201984 ..0..3....1..2....0..3....3.-3...-1..3....1..3....2..3...-1..2....2..1...-1..0 %e A201984 ..0..3....3..2....2.-2....3.-1....2..0....2..1....3..0....2..3....3.-1....2..1 %K A201984 nonn %O A201984 1,1 %A A201984 _R. H. Hardin_ Dec 07 2011